Power wave transmission techniques to focus wirelessly delivered power at a receiving device

ABSTRACT

An example method performed by a wireless-power-transmitting device that includes an antenna array is provided. The method includes radiating electromagnetic waves that form a maximum power level at a first distance away from the antenna array. Moreover, a power level of the radiated electromagnetic waves decreases, relative to the maximum power level, by at least a predefined amount at a predefined radial distance away from the maximum power level. In some embodiments, the method also includes detecting a location of a wireless-power-receiving device, whereby the location of the wireless-power-receiving device is further from the antenna array than a location of the maximum power level.

RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/689,745, filed Jun. 25, 2018, entitled “Antenna Structures,Antenna Array Configurations, and Power Wave Transmission Techniques toFocus Wirelessly Delivered Power at a Receiving Device,” which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure also relates generally to antenna structures,antenna array configurations (e.g., arrays with co-polarized antennagroups that produce perpendicularly oriented radiation patterns), andpower wave transmission techniques to focus wirelessly-delivered powerat a receiving device.

BACKGROUND

Portable electronic devices such as smartphones, tablets, notebooks andother electronic devices have become a necessity for communicating andinteracting with others. The frequent use of portable electronicdevices, however, uses a significant amount of power, which quicklydepletes the batteries attached to these devices. Inductive chargingpads and corresponding inductive coils in portable devices allow usersto wirelessly charge a device by placing the device at a particularposition on an inductive pad to allow for a contact-based charging ofthe device due to magnetic coupling between respective coils in theinductive pad and in the device.

Conventional inductive charging pads, however, suffer from manydrawbacks. For one, users typically must place their devices at aspecific position and in a certain orientation on the charging padbecause gaps (“dead zones” or “cold zones”) exist on the surface of thecharging pad. In other words, for optimal charging, the coil in thecharging pad needs to be aligned with the coil in the device in orderfor the required coupling to occur. This results in a frustratingexperience for many users as they may be unable to properly charge theirdevices, or may assume that their device is charging but will later findout that the device was not properly positioned on an inductive chargingpad and therefore did not receive any charge at all.

Charging using electromagnetic radiation (e.g., microwave radiationpower waves) offers promise, but antenna elements used in antenna arraysfor RF, at-a-distance charging typically suffer from inefficienciescaused by mutual coupling between neighboring antenna elements,especially when spacing between adjacent elements is minimized (e.g.,smaller than a half-wavelength). Moreover, evolving governmentregulations from governments around the world (which must be compliedwith to legally sell products in various jurisdictions around the world,and to ensure that the radiation is transmitted in a safe manner)typically require that wireless power transfer using electromagneticradiation focus power around a receiving element and suppress radiationelsewhere. Because these regulations are not well-defined and areconstantly evolving and because of physical constraints of conventionaltransmission techniques (e.g., defocusing effects), designing apower-transmission device that will comply with these regulations is avery difficult proposition.

SUMMARY

Accordingly, there is a need for a wireless transmission solution thatsubstantially reduces mutual coupling between neighboring (e.g.,adjacent) antenna elements in densely populated antenna arrays. Onesolution, as disclosed herein, is for neighboring antenna elements to beco-polarized, and also for the neighboring antenna elements to producefirst and second electromagnetic radiation patterns that areperpendicularly oriented relative to one another. In such aconfiguration, it has been discovered that mutual coupling betweenneighboring antenna elements is reduced substantially, such that effectscaused by mutual coupling are negligible. In light of this, antennaarrays that implement this principle can be miniaturized as the antennaelements that compose the antenna array are less susceptible to mutualcoupling (which would further negatively impact antenna performance(e.g., radiation efficiency), especially for very small antennaelements), and therefore can be tightly packed together. Example antennaarray designs for accomplishing the solution are described below.

(A1) In some embodiments, an antenna array (e.g., antenna array 110-1,FIG. 1) includes first and second antennas that: (i) are spaced-apart,(ii) co-polarized, and (iii) are configured to produce first and secondelectromagnetic (“EM”) radiation patterns, respectively. The first EMradiation pattern has a higher concentration of EM energy produced alongorthogonal first and second axes relative to a concentration of EMenergy produced along a third axis orthogonal to the first and secondaxes, and the second EM radiation pattern has a higher concentration ofEM energy produced along the first and third axes relative to aconcentration of EM energy produced along the second axis. The first andsecond antennas, at least in some embodiments, are the antennastructures discussed below in Section C. Further, non-limiting examplesarrangement of the first and second antennas are illustrated in FIGS. 5,6A, 7A, 8A, and 9A-1 to 9A-3.

(A2) In some embodiments of the antenna array of A1, the first antennais a first antenna type, and the second antenna is a second antenna typedifferent from the first antenna type.

(A3) In some embodiments of the antenna array of any of A1-A2, the firstand second EM radiation patterns are formed by EM waves having afrequency and a wavelength (λ). Further, the first and second antennasare spaced-part by a distance that is less than (λ/2) and a couplingeffect between the first and second antennas is less than −10 decibels(dB) when the first and second antennas are respectively radiating theEM waves that form the first and second radiation patterns.

(A4) In some embodiments of the antenna array of any of A1-A3, thedistance is less than 1/10 lambda.

(A5) In some embodiments of the antenna array of any of A1-A4, thedistance is less than 1/15 lambda.

(A6) In some embodiments of the antenna array of any of A1-A5, thedistance is less than 1/30 lambda.

(A7) In some embodiments of the antenna array of any of A1-A6, thecoupling effect between the first and second antennas is betweenapproximately −10 dB to −24 dB.

(A8) In some embodiments of the antenna array of any of A1-A7, thecoupling effect between the first and second antennas is betweenapproximately −15 dB to −24 dB.

(A9) In some embodiments of the antenna array of any of A1-A8, thecoupling effect between the first and second antennas is betweenapproximately −20 dB to −24 dB.

(A10) In some embodiments of the antenna array of any of A1-A9, thefirst and second antennas each include (i) opposing first and secondsurfaces and (ii) a transmitting element. Further, the respective firstsurfaces are coupled to a base through which a feeding element extendsto provide an EM signal to the respective transmitting elementpositioned on the respective second surfaces. In some embodiments, therespective second surfaces are substantially co-planar with one another.

(A11) In some embodiments of the antenna array of any of A1-A10, thefirst and second antennas form a first antenna group and the antennaarray further includes a second antenna group, including: (i) a thirdantenna configured to radiate one or more third EM waves that form athird radiation pattern, and (ii) a fourth antenna, spaced-apart fromthe third antenna by the distance, configured to radiate one or morefourth EM waves that form a fourth radiation pattern. The first, second,third, and fourth antennas are co-polarized.

(A12) In some embodiments of the antenna array of A11, the first andsecond antennas are spaced apart by a first non-zero distance, and thefirst antenna group is spaced-apart from the second antenna group by asecond non-zero distance greater than the first non-zero distance.

(A13) In some embodiments of the antenna array of any of A11-A12, thefirst and second antenna groups are collinearly aligned along a firstaxis, and the first and second antenna groups are offset along a secondaxis, orthogonal to the first axis, by the second distance.

(A14) In some embodiments of the antenna array of any of A11-A13, thefirst and third antennas have a first orientation, and the second andfourth antennas have a second orientation.

(A15) In some embodiments of the antenna array of any of A11-A13, anorientation of the first and second antennas mirrors an orientation ofthe third and fourth antennas, respectively.

(A16) In some embodiments of the antenna array of any of A11-A13, anorientation of the first and second antennas is rotated 180 degreesrelative to an orientation of the third and fourth antennas,respectively.

(A17) In some embodiments of the antenna array of A11, the first andsecond antennas are spaced apart by a first non-zero distance, and thefirst antenna group is spaced-apart from the second antenna group by asecond non-zero distance less than the first non-zero distance.

(A18) In some embodiments of the antenna array of A17, the first andfourth antennas are adjacent to one another and spaced-apart by thesecond non-zero distance, and the second and third antennas are adjacentto one another and spaced-apart by the second non-zero distance.

(A19) In some embodiments of the antenna array of any of A1-A18, thefirst and second EM radiation patterns combine to form a third EMradiation pattern when the first and second antennas produce the firstand second EM radiation patterns, respectively. Further, when a receiverdevice is positioned within a predefined distance from the antenna arrayand in the path of the third EM radiation pattern, the receiver deviceuses energy from the third EM radiation pattern to power or charge thereceiver device.

Below are some example antennas that can be used in the antenna array ofany of A1-A19.

(B1) In some embodiments, an antenna (e.g., antenna 1000, antenna 1100,antenna 1500, or antenna 1600) for radiating electromagnetic waveshaving a wavelength (λ), includes: (i) a substrate having a largestdimension (e.g., a cross-sectional dimension) that is less thanapproximately 0.25λ in length, (ii) first and second pins extending fromthe substrate, (iii) a first radiating element offset from the substrateby a first distance and coupled to the first and second pins, the firstradiating element following a first meandering pattern, and (iv) asecond radiating element offset from the substrate by a second distancegreater than the first distance and coupled to the first radiatingelement, the second radiating element following a second meanderingpattern. In some embodiments, the first and second radiating elementsare positioned within a border of the substrate. Furthermore, in someembodiments, the first radiating element includes first and secondelements (e.g., arms, branches) that can be symmetrical (e.g., first andsecond radiating elements 1004 and 1006, FIG. 10A; lower elements 1518-1and 1518-2, FIG. 15D) or unsymmetrical. In some embodiments, thesubstrate includes one or more traces adapted to apply a phase shift tosome of the electromagnetic waves radiated by the antenna (e.g., phaseshifting line 1508, FIG. 15B).

(C1) In some embodiments, an antenna (e.g., antenna 1000, antenna 1100,antenna 1500, or antenna 1600) for radiating electromagnetic waveshaving a wavelength (λ), includes (i) a substrate having a largestdimension (e.g., a cross-sectional dimension) that is less thanapproximately 0.25λ in length, (ii) first and second pins that arecoupled to the substrate, (iii) a first radiating element, offset fromthe substrate by a first distance and coupled to the first pin, thatfollows a first meandering pattern, (iv) a second radiating element,offset from the substrate by a second distance and coupled to the secondpin, that follows a second meandering pattern mirroring the firstmeandering pattern, and (v) a third radiating element, offset from thesubstrate by a third distance greater than the first and seconddistances, that follows a third meandering pattern.

Furthermore, in some embodiments, (i) the first radiating element iscoupled to a first end portion of the third radiating element, (ii) thesecond radiating element is coupled to a second end portion, differentfrom the first end portion, of the third radiating element, and (iii)the first, second, and third radiating elements are positioned within aborder of the substrate.

(C2) In some embodiments of the antenna of C1, the first and secondradiating elements are co-planar, and the first and second distances arethe same.

(C3) In some embodiments of the antenna of any of C1-C2, the thirdmeandering pattern substantially mirrors a combination of the first andsecond meandering patterns. In some embodiments, an overall length ofthe third meandering pattern is approximately 1λ. Alternatively, in someembodiments, an overall length of the third meandering pattern isgreater than (or less than) 1λ.

(C4) In some embodiments of the antenna of any of C1-C3, the substrateincludes a first half and a second half, the first pin is positioned inthe first half of the substrate, and the second pin is positioned in thesecond half of the substrate. Further, the first radiating element ispositioned in the first half of the substrate, and the second radiatingelement is positioned in the second half of the substrate.

(C5) In some embodiments of the antenna of any of C1-C4, the first,second, and third radiating elements include a plurality of coplanarsegments, each of the plurality of coplanar segments including: a firstsegment defined in a first direction, a second segment defined in asecond direction perpendicular to the first direction, and a thirdsegment defined in the first direction.

(C6) In some embodiments of the antenna of C5, the plurality of coplanarsegments is a plurality of continuous segments.

(C7) In some embodiments of the antenna of C5, the plurality of coplanarsegments is a plurality of contiguous segments.

(C8) In some embodiments of the antenna of any of C1-C7, the first pinis coupled to an EM (e.g., a radio frequency) signal port and the secondpin is a grounding pin. For example, the first pin may be coupled, viathe EM port, to one or more power amplifiers and/or power feedingcircuitry.

(C9) In some embodiments of the antenna of any of C1-C8, the thirdradiating element includes first and second end pieces (e.g., tabs1010-A, 1010-B, FIG. 10A; folds 1517, FIG. 15D) coupled with the firstand second radiating elements, respectively, and the first and secondend pieces differ in shape from a body of the third radiating element.Alternatively, in some embodiments, the end pieces are distinct piecesof the antenna. Alternatively, in some embodiments, the end pieces arepart of the first and/or second radiating elements.

(C10) In some embodiments of the antenna of any of C1-C9, the substrateis a first substrate, and the antenna further includes a secondsubstrate having opposing first and second surfaces, offset from thefirst substrate. Moreover, the first and second radiating elements areattached to the first surface of the second substrate, and the thirdradiating element is attached to the second surface of the secondsubstrate.

(C11) In some embodiments of the antenna of C10, the first and secondradiating elements each includes (i): two parallel segments spaced apartand not directly coupled to each other, and (ii) a plurality ofconnectors (e.g., tuning elements 1120 and 1122, FIG. 11A) disposed inan area between the two parallel segments, where each of the pluralityof connectors is (i) perpendicular to the two parallel segments and (ii)switchably coupled to the two parallel segments. Alternatively or inaddition, in some embodiments, the third radiating element includes (i):two parallel segments spaced apart and not directly coupled to eachother, and (ii) a plurality of connectors (e.g., tuning elements 1120and 1122, FIG. 11A) disposed in an area between the two parallelsegments, where each of the plurality of connectors is (i) perpendicularto the two parallel segments and (ii) switchably coupled to the twoparallel segments.

(C12) In some embodiments of the antenna of C11, the first and secondradiating elements are tuned to a first frequency when a first connectorof the plurality of connectors is switchably coupled to the two parallelsegments, and the first and second radiating elements are tuned to asecond frequency, different from the first frequency, when a secondconnector, different from the first connector, of the plurality ofconnectors is switchably coupled to the two parallel segments. Further,in those embodiments where the third radiating element includes theplurality of connectors, the third radiating element may also be tunedto various frequencies.

(C13) In some embodiments of the antenna of any of C10-C12, the firstand second radiating elements (and/or the third radiating element) eachincludes a plurality of tuning elements switchably coupled to oneanother in series (e.g., tuning elements 1124 and 1126, FIG. 11A).

(C14) In some embodiments of the antenna of any of C10-C13, furtherincluding first and second vias extending through the second substrateto couple the first radiating element with the third radiating elementand the second radiating element with the third radiating element,respectively.

(C15) In some embodiments of the antenna of any of C1-C9, the first,second, and third radiating elements are made from stamped metal.

(C16) In some embodiments of the antenna of any of C1-C9 and C15,further including dielectric support material disposed periodicallybetween (i) the first radiating element and the third radiating element,and (ii) the second radiating element and the third radiating element.

(C17) In some embodiments of the antenna of any of C1-C9 and C15-C16,further including additional dielectric support material disposedperiodically between the first and second radiating elements and thesubstrate.

(D1) In some embodiments, an antenna (e.g., antenna 1200 and antenna1400) for radiating electromagnetic waves having a wavelength (λ),includes (i) a substrate including first and second opposing surfaces,the first surface including at least one edge that is less thanapproximately 0.2λ in length, (ii) a radiating element coupled to thefirst surface of the substrate and separated from the at least one edgeby a non-zero distance, the radiating element defining first and seconddistinct cutouts, and (iii) a feed, defined through the substrate,coupling the radiating element to transmission circuitry. In someembodiments, the antenna further includes one or more tuning elementsswitchably (or non-switchably) connected to the radiating element, theone or more tuning elements being configured to adjust an operatingfrequency of the radiating element.

(D2) In some embodiments of the antenna of D1, the first cutout has afirst shape, and the second cutout has a second shape distinct from thefirst shape.

(D3) In some embodiments of the antenna of any of D1-D2, wherein alength of an edge of the radiating element is shorter than the length ofthe at least one edge.

(D4) In some embodiments of the antenna of any of D1-D3, the firstcutout is a circular cutout, and the one or more tuning elements includea plurality of concentric rings positioned within the circular cutout.

(D5) In some embodiments of the antenna of D4, adjusting the operatingfrequency of the radiating element includes connecting a firstconcentric ring of the plurality of concentric rings to the radiatingelement, and connecting the first concentric ring changes the operatingfrequency of the radiating element from a first frequency to a secondfrequency greater than the first frequency. In some embodiments,changing the number of points connecting the first concentric ring tothe radiating element changes the value of the frequency (i.e., changesa difference between the first and second frequencies).

(D6) In some embodiments of the antenna of D5, adjusting the operatingfrequency of the radiating element further includes connecting two ormore concentric rings of the plurality of concentric rings to theradiating element, the two or more concentric rings including the firstconcentric ring, and connecting the two or more concentric rings changesthe operating frequency of the radiating element from the secondfrequency to a third frequency greater than the second frequency.

(D7) In some embodiments of the antenna of D4, the circular cutout has afirst radius, and the plurality of concentric rings includes: (i) afirst concentric ring, switchably connected to the radiating element,having a second radius smaller than the first radius, and a secondconcentric ring, switchably connected to the first concentric ring,having a third radius smaller than the second radius.

(D8) In some embodiments of the antenna of D4, the plurality ofconcentric rings includes four concentric rings.

(D9) In some embodiments of the antenna of any of D1-D3, the one or moretuning elements include a plurality of rectangular segments on the firstsurface of the substrate, and at least one of the plurality ofrectangular segments is positioned along the at least one edge of thefirst surface of the substrate.

(D10) In some embodiments of the antenna of D9, adjusting the operatingfrequency of the radiating element includes connecting a firstrectangular segment of the plurality of rectangular segments to theradiating element, and connecting the first rectangular segment changesthe operating frequency of the radiating element from a first frequencyto a second frequency less than the first frequency. The firstrectangular segment may be switchably connected to or non-switchablyconnected to the radiating element.

(D11) In some embodiments of the antenna of D10, adjusting the operatingfrequency of the radiating element further includes connecting two ormore rectangular segments of the plurality of rectangular segments tothe radiating element, the two or more rectangular segments includingthe first rectangular segment, and connecting the two or morerectangular segments changes the operating frequency of the radiatingelement from the second frequency to a third frequency less than thesecond frequency.

(D12) In some embodiments of the antenna of any of D1-D3, the one ormore tuning elements include: (i) a plurality of concentric ringspositioned within the first cutout, and (ii) a plurality of rectangularsegments on the first surface of the substrate. Furthermore, adjustingthe operating frequency of the radiating element includes: (i)connecting at least one of the plurality of concentric rings to theradiating element, and (ii) connecting at least one of the plurality ofrectangular segments to the radiating element.

(D13) In some embodiments of the antenna of D12, said connecting changesthe operating frequency of the radiating element from a first frequencyto a second frequency different from the first frequency.

(D14) In some embodiments of the antenna of any of D1-D13, the one ormore tuning elements are configured to adjust the operating frequency ofthe radiating element based on signals from a controller managingoperation of the antenna.

(D15) In some embodiments of the antenna of any of D1-D14, the substratefurther includes a plurality of layers, and each layer of the pluralityof layers has at least one edge that is aligned with the at least oneedge of the first surface. The plurality of layers is stacked betweenthe first and seconds surfaces of the substrate.

(D16) In some embodiments of the antenna of D15, further including oneor more shorting vias, defined through the substrate, for coupling thefirst surface with the plurality of layers.

(D17) In some embodiments of the antenna of any of D1-D16, the radiatingelement is printed onto the first surface of the substrate, and thesecond surface of the substrate operates as a ground plane.

Further, there is also a need for a wireless transmission solution thatcomplies with regulations that are constantly evolving and thatovercomes physical constraints of conventional transmission techniques(e.g., defocusing effects). One solution is for antenna arrays (e.g.,the antenna array of any of A1-A19) to compensate for anticipateddefocusing by transmitting electromagnetic waves to different focalpoints. The precise locations of the different focal points aredetermined by a transmitter (e.g., transmitter 102, FIG. 2A) based on alocation of a receiver device relative to the antenna array. In doingso, the transmitter is able to diminish effects of defocusing, and as aresult, the transmitter's antenna array is able to transmitelectromagnetic waves that sufficiently focus radiated energy at areceiver's location in compliance with respective governing regulationsset by various agencies, e.g., the Federal Communications Commission(FCC) in the United States or the European Commission in the EuropeanUnion. Methods of operating one such example transmitter (a“wireless-power-transmitting device”) are described below.

(E1) In some embodiments, a method of wirelessly charging awireless-power-receiving device includes, providing awireless-power-transmitting device including an antenna array, theantenna array including a first antenna group of at least two antennasand a second antenna group of at least two antennas distinct from thefirst antenna group, where the wireless-power-transmitting device is incommunication with a controller. The method further includes, based on alocation of a wireless-power-receiving device, selecting by thecontroller: (i) a first value for a first transmission characteristicthat is used for transmission of electromagnetic waves by the at leasttwo antennas in the first antenna group, and (ii) a second value,distinct from the first value, for the first transmission characteristicthat is used for transmission of electromagnetic waves by the at leasttwo antennas in the second antenna group. The method further includes(i) transmitting to the location of the wireless-power-receiving device,by the at least two antennas in the first antenna group, firstelectromagnetic waves with the first value for the first transmissioncharacteristic, and (ii) transmitting to a focal point that is furtherfrom the wireless-power-transmitting device than the location of thewireless-power-receiving device, by the at least two antennas in thesecond antenna group, second electromagnetic waves with the second valuefor the first transmission characteristic. The wireless-power-receivingdevice uses energy from at least the first electromagnetic waves topower or charge the wireless-power-receiving device.

(E2) In some embodiments of the method of E1, the antenna array furtherincludes a third antenna group of at least two antenna elements, and themethod further includes: transmitting, to the focal point that isfurther from the wireless-power-transmitting device than the location ofthe wireless-power-receiving device, by the at least two antennas in thethird antenna group, third electromagnetic waves with the second valuefor the first transmission characteristic. Alternatively, in someembodiments, the method further includes: transmitting, to the focalpoint that is further from the wireless-power-transmitting device thanthe location of the wireless-power-receiving device, by the at least twoantennas in the third antenna group, third electromagnetic waves with athird value for the first transmission characteristic, where the thirdvalue is different from the second value.

(E3) In some embodiments of the method of E2, the first antenna group ispositioned between the second and third antenna groups within theantenna array, and the first antenna group is separated from the secondand third antenna groups by at least a non-zero spacing distance.

(E4) In some embodiments of the method of any of E2-E3, the second valueis greater than the first value.

(E5) In some embodiments of the method of any of E2-E4, the firsttransmission characteristic is amplitude. As one example, the firsttransmission characteristic is amplitude (e.g., to manipulate powerlevels) for the transmission of electromagnetic waves, and thecontroller selects the values to be used by each of the groups ofantennas for this first transmission characteristic. In someembodiments, the controller may select additional values for othertransmission characteristics as well. For example, the controller mayalso select respective values for phase, gain, polarization, frequency,etc.

(E6) In some embodiments of the method of any of E2-E5, the selectingalso includes selecting respective phase settings for (i) each antennaof the at least two antennas in the first antenna group, (ii) eachantenna of the at least two antennas in the second antenna group, and(iii) each antenna of the at least two antennas in the third antennagroup. The first, second, and third electromagnetic waves aretransmitted using the respective phase settings.

(E7) In some embodiments of the method of E6, respective phase settingsfor the at least two antennas in the second antenna group and respectivephase settings for the at least two antennas of the third antenna groupare the same.

(E8) In some embodiments of the method of any of E3-E7, the second andthird antenna groups include a same number of antennas, and the firstantenna group includes fewer than the same number of antennas.

(E9) In some embodiments of the method of any of E1-E8, the location ofthe wireless-power-receiving device is positioned along an axisextending away from the antenna array, and the focal point is furtherfrom the antenna array along the axis.

(E10) In some embodiments of the method of any of E1-E9, the at leasttwo antennas in the first antenna group and the at least two antennas inthe second antenna group are co-planar. Further, in some embodiments,antennas within each group are also co-polarized and have perpendicularradiation patterns, such as the antenna array of any of A1-A19.

(E11) In some embodiments of the method of any of E1-E10, the first andsecond values are predetermined.

(E12) In some embodiments of the method of any of E1-E11, the first andsecond values are stored in a lookup table, and selecting the first andsecond values includes obtaining, by the controller, the first andsecond values from the lookup table.

(E13) In some embodiments of the method of any of E1-E12, transmissionof the first and second electromagnetic waves generates: (i) a localminimum of electromagnetic energy at a first distance from the antennaarray, and (ii) a local maximum of electromagnetic energy at a seconddistance greater than the first distance from the antenna array. Thelocation of the wireless-power-receiving device is at a third distancegreater that the second distance from the antenna array.

(E14) In some embodiments of the method of E13, the first and secondelectromagnetic waves have a wavelength (λ), and a difference betweenthe second and third distances is less than or equal to 1λ.

(E15) In some embodiments of the method of E14, the local maximum ofelectromagnetic energy has a first power level, and transmission of thefirst and second electromagnetic waves generates a sphere ofelectromagnetic energy having a second power level at a distance of 1λfrom the local maximum. The second power level is less than the firstpower level by a predetermined amount (in other words, thewireless-power-transmitting device is able to produce a roll-off ofpower level away from the local maximum of electromagnetic energy andthat roll-off is by, e.g., 3 dB (an example of the predetermined amount)at 1λ from the local maximum.

(E16) In some embodiments of the method of any of E2-E7, the at leasttwo antennas in the first antenna group are positioned in a centralregion of the antenna array, and respective at least two antennas ofeach of the second and third antenna groups are positioned in opposingedge regions of the antenna array.

(E17) In some embodiments of the method of any of E1-E16, the selectingis performed upon determining that the wireless-power-receiving deviceis located within a wireless-power-transmission range of thewireless-power-transmitting device.

(E18) In some embodiments of the method of any of E1-E17, furtherincluding receiving, via an antenna of the antenna array, a signal fromthe wireless-power-receiving device, detecting a phase of the signal,and determining, by the controller, the location of thewireless-power-receiving device relative to the antenna array based onthe phase of the signal.

(E19) In some embodiments of the method of any of E1-E18, theelectromagnetic waves are transmitted at a frequency of approximately5.8 GHz, 2.4 GHz, or 900 MHz.

In some embodiments, the first and second antenna groups of thewireless-power-transmitting device described in E1-E19 above eachrespectively include the first and second antennas described in A1.Various modifications may also be made to thewireless-power-transmitting device to include the features described inA2-A19.

(E20) In one other aspect, a wireless power transmitter is provided, andthe wireless power transmitter includes the structural characteristicsfor a wireless-power-transmitting device described above in any ofE1-E19 or below in any of F1-F10, and the wireless power transmitter isalso configured to perform the method steps described above in any ofE1-E19 or below in any of F1-F10.

(E21) In another aspect, a wireless power transmitter that includes oneor more of the antenna arrays described in any of A1-A19 is provided. Insome embodiments, the wireless power transmitter is in communicationwith one or more processors and memory storing one or more programswhich, when executed by the one or more processors, cause the wirelesspower transmitter to perform the method described in any one of E1-E19or below in any of F1-F10.

(E22) In yet another aspect, a wireless power transmitter (that includesone or more of the antenna arrays described in any of A1-A19) isprovided and the wireless power transmitter includes means forperforming the method described in any one of E1-E19 or below in any ofF1-F10.

(E23) In still another aspect, a non-transitory computer-readablestorage medium is provided (e.g., as a memory device, such as externalor internal storage, that is in communication with a wireless powertransmitter). The non-transitory computer-readable storage medium storesexecutable instructions that, when executed by a wireless powertransmitter (that includes one or more of the antenna arrays describedin any of A1-A19) with one or more processors/cores, cause the wirelesspower transmitter to perform the method described in any one of E1-E19or below in any of F1-F10.

(F1) In some embodiments, another method of wirelessly charging awireless-power-receiving device includes providing awireless-power-transmitting device that includes an antenna array (e.g.,antenna array of any of A1-A19). The method includes radiatingelectromagnetic waves that form a maximum power level at a firstdistance away (e.g., 1 wavelength away from thewireless-power-transmitting device, the wavelength being defined basedon an operating frequency of the antenna array) from the antenna array.Further, a power level of the radiated electromagnetic waves decreases,relative to the maximum power level, by at least a predefined amount(e.g., 3 dB, 2 dB, 1 dB, 0.5 dB, or another predefined amount based ongoverning regulations and desired power focusing) at a radial distanceaway from the maximum power level. The radial distance may bepredefined.

(F2) In some embodiments of the method of F1, a wireless-power-receivingdevice is located a second distance, greater than the first distance,away from the antenna array, and the wireless-power-receiving device islocated within, at least partially, the predefined radial distance awayfrom the maximum power level.

(F3) In some embodiments of the method of F2, thewireless-power-receiving device uses energy from the radiatedelectromagnetic waves to power or charge the wireless-power-receivingdevice.

(F4) In some embodiments of the method of any of F1-F3, the decrease inthe power level of the radiated electromagnetic from the maximum powerlevel is a monotonic decrease.

(F5) In some embodiments of the method of any of F1-F4, the radiatedelectromagnetic waves have a frequency and a wavelength (λ), and thepredefined radial distance ranges from approximately 0.5λ to 2λ.Alternatively, in some embodiments, the predefined radial distanceranges from approximately 0.5 feet to 2 feet.

(F6) In some embodiments of the method of F5, the predefined radialdistance is approximately 1λ.

(F7) In some embodiments of the method of any of F1-F6, the method alsoincludes, before radiating the electromagnetic waves: detecting (ordetermining) a location of a wireless-power-receiving device. Thelocation of the wireless-power-receiving device is further from theantenna array than a location of the maximum power level.

(F8) In some embodiments of the method of F7, the method furtherincludes, after detecting the location of the wireless-power-receivingdevice and before radiating the electromagnetic waves: determiningsettings for the electromagnetic waves based on the location of thewireless-power-receiving device relative to the antenna array. Thedetermined settings for the electromagnetic waves may include values forone or more transmission characteristics.

(F9) In some embodiments of the method of F8, the electromagnetic wavesare radiated using the determined settings.

(F10) In some embodiments of the method of F9, the antenna arrayincludes first and second groups of antennas and radiating theelectromagnetic waves includes: (i) radiating a first plurality ofelectromagnetic waves from antenna elements in the first group ofantennas using first settings from the determined settings, wherein afirst transmission focal point for the antenna elements in the firstgroup of antennas is the location of the wireless-power-receivingdevice, and (ii) radiating a second plurality of electromagnetic wavesfrom antenna elements in the second group of antennas using secondsettings, different from the first settings, from the determinedsettings. The antenna elements in the second group of antennas have asecond transmission focal point that is another location that is furtherfrom the antenna array than the location of the wireless-power-receivingdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the present disclosure can be understood in greater detail, amore particular description may be had by reference to the features ofvarious embodiments, some of which are illustrated in the appendeddrawings. The appended drawings, however, merely illustrate pertinentfeatures of the present disclosure and are therefore not to beconsidered limiting, for the description may admit to other effectivefeatures.

FIG. 1 is a block diagram illustrating a representative wireless powertransmission system that produces a desired power focusing in accordancewith some embodiments.

FIG. 2A is a block diagram illustrating a representativewireless-power-transmitting device in accordance with some embodiments.

FIG. 2B is a block diagram illustrating a representativewireless-power-receiving device (also referred to simply as a receiverin this description) in accordance with some embodiments.

FIG. 3A illustrates an example duplet of co-polarized antennas thatproduce perpendicularly-oriented radiation patterns in accordance withsome embodiments.

FIGS. 3B-1 and 3B-2 illustrate radiation patterns generated by the firstand second antennas of FIG. 3A, respectively, in accordance with someembodiments.

FIG. 3C illustrates a resulting radiation pattern produced by the firstand second antennas of FIG. 3A in accordance with some embodiments.

FIG. 3D illustrates a cross-sectional view of the resulting radiationpattern of FIG. 3C (taken along the X-Z plane shown in FIG. 3C), inaccordance with some embodiments.

FIG. 3E is a diagram that illustrates mutual coupling between the firstand second antennas depicted in FIG. 3A in accordance with someembodiments.

FIGS. 4A-4E illustrate the detrimental effects caused by mutual couplingin antenna arrays using some conventional antennas.

FIG. 5 illustrates an example antenna duplet in accordance with someembodiments.

FIG. 6A illustrates an example antenna duplet in accordance with someembodiments.

FIGS. 6B-1 and 6B-2 illustrate radiation patterns generated byindividual antennas of the example antenna duplet of FIG. 6A,respectively, in accordance with some embodiments.

FIG. 6C illustrates a resulting radiation pattern for the exampleantenna duplet of FIG. 6A in accordance with some embodiments.

FIG. 6D illustrates a cross-sectional view of the resulting radiationpattern of FIG. 6C (taken along the X-Z plane shown in FIG. 6C), inaccordance with some embodiments.

FIG. 6E is a diagram that illustrates beneficial mutual coupling effectsbetween the individual antennas of the example antenna duplet depictedin FIG. 6A, in accordance with some embodiments.

FIGS. 7A-9E illustrate various antenna array configurations using theantenna duplet illustrated in FIG. 6A (and associated characteristics ofthese various antenna array configurations) in accordance with someembodiments.

FIGS. 10A-10C illustrate various views showing a first embodiment of adrop-in antenna.

FIG. 10D illustrates a radiation pattern generated by the firstembodiment of the drop-in antenna depicted in FIG. 10A.

FIG. 10E illustrates a cross-sectional view of the radiation patternshown in FIG. 10D (taken along the X-Z plane shown in FIG. 10D), inaccordance with some embodiments.

FIG. 10F illustrates a cross-sectional view of the radiation patternshown in FIG. 10D (taken along the Y-Z plane shown in FIG. 10D), inaccordance with some embodiments.

FIGS. 11A-11B illustrate various views showing a second embodiment of adrop-in antenna.

FIGS. 11C-1 to 11C-3 illustrate various coupling diagrams for the secondembodiment of the drop-in antenna when it is operating at differentfrequencies.

FIGS. 12A-12D illustrate various views showing a third embodiment of adrop-in antenna.

FIGS. 12E-1 and 12E-2 illustrate various configurations of tuningelements of the third embodiment of the drop-in antenna in accordancewith some embodiments.

FIGS. 12F-12H illustrate various coupling diagrams for the thirdembodiment of the drop-in antenna when it is operating at differentfrequencies.

FIG. 13A illustrates a dual-polarized antenna, in accordance with someembodiments drop-in antenna.

FIG. 13B-1 shows a radiation pattern produced by the dual-polarizedantenna depicted in FIG. 13A.

FIG. 13B-2 is a diagram that shows mutual coupling effects for thedual-polarized antenna, in accordance with some embodiments.

FIG. 13C shows a cross-sectional view of a radiation pattern produced bythe dual-polarized antenna depicted in FIG. 13A when port 1306-1 isactive.

FIG. 13D shows a cross-sectional view of a radiation pattern produced bythe dual-polarized antenna in FIG. 13A when port 1306-2 is active.

FIG. 13E shows an example of an antenna array that includes a group ofthe dual-polarized antennas.

FIG. 13F shows a diagram representing mutual coupling effects measuredbetween different ports within the antenna array of FIG. 13E.

FIG. 13G shows radiation patterns produced by the antenna array of FIG.13E.

FIGS. 14A-1 and 14A-2 illustrate embodiments of an air-suspendedcapacitor-loaded patch antenna in accordance with some embodiments.

FIG. 14B illustrates a top view of the air-suspended capacitor-loadedpatch antenna, in accordance with some embodiments.

FIG. 14C illustrates a cross-sectional view of the air-suspendedcapacitor-loaded patch antenna, in accordance with some embodiments.

FIG. 14D shows a radiation pattern produced by the antenna 1400, inaccordance with some embodiments.

FIG. 14E is a cross-sectional view of the radiation pattern shown inFIG. 14D.

FIG. 14F shows a diagram representing the magnitude of the reflectioncoefficient measured at the feed port for the air-suspendedcapacitor-loaded patch antenna.

FIGS. 15A-15E illustrate a first embodiment of a multidimensional dipoleantenna over folded shield an.

FIG. 15F shows a radiation pattern produced by the first embodiment ofthe multidimensional dipole antenna over folded shield.

FIG. 15G shows a diagram representing mutual coupling effects measuredbetween a port and itself within the first embodiment of themultidimensional dipole antenna over folded shield.

FIGS. 15H-1 to 15H-3 show various example array configurations, inaccordance with some embodiments. FIG. 15I shows transmissioncharacteristics for the example array configuration depicted in FIG.15H-1. FIGS. 15J and 15K show transmission characteristics for theexample array configuration depicted in FIG. 15H-2.

FIGS. 16A-16B illustrate a second embodiment of a multidimensionaldipole antenna over folded shield in accordance with some embodiments.

FIG. 16C shows a radiation pattern produced by the second embodiment ofthe multidimensional dipole antenna over folded shield.

FIG. 16D is a cross-sectional view of the radiation pattern shown inFIG. 16C.

FIG. 16E shows a diagram representing mutual coupling effects measuredbetween a port and itself within the second embodiment of themultidimensional dipole antenna over folded shield.

FIG. 17A illustrates a two-dimensional representation of a sphere ofelectromagnetic energy that is produced by an antenna array, inaccordance with some embodiments.

FIG. 17B is a diagram 1700 that depicts power density levels relative todistance from the antenna array shown in FIG. 17A, in accordance withsome embodiments.

FIG. 17C is a diagram that shows power profiles with different localmaxima, in accordance with some embodiments.

FIG. 18A is a block diagram illustrating a representative wireless powertransmission system having four antenna groups in its antenna array inaccordance with some embodiments.

FIGS. 18B-18G are diagrams that illustrate various power profiles thatcan be created by the antenna array of FIG. 18A, in accordance with someembodiments.

FIGS. 19A-19E are block diagrams illustrating a representative wirelesspower transmission system having an antenna array that uses differentfocal points for different antenna groups within the antenna array basedon a receiver's location, in accordance with some embodiments.

FIG. 20 is a flow diagram showing a method of wireless powertransmission in accordance with some embodiments.

FIG. 21 is another flow diagram showing a method of wireless powertransmission in accordance with some embodiments.

In accordance with common practice, the various features illustrated inthe drawings may not be drawn to scale. Accordingly, the dimensions ofthe various features may be arbitrarily expanded or reduced for clarity.In addition, some of the drawings may not depict all of the componentsof a given system, method or device. Finally, like reference numeralsmay be used to denote like features throughout the specification andfigures.

DETAILED DESCRIPTION

Numerous details are described herein in order to provide a thoroughunderstanding of the example embodiments illustrated in the accompanyingdrawings. However, some embodiments may be practiced without many of thespecific details, and the scope of the claims is only limited by thosefeatures and aspects specifically recited in the claims. Furthermore,well-known processes, components, and materials have not been describedin exhaustive detail so as not to unnecessarily obscure pertinentaspects of the embodiments described herein.

For ease of explanation, the description that follows is broken into thefollowing sections: A) Example Wireless Power Transmission Systems; B)Example Antenna Array Configurations, Including Example Antenna Arrayswith Co-Polarized Antenna Groups that Produce Perpendicularly OrientedRadiation Patterns, C) Drop-in Antenna Structures, D) Dual-PolarizedAntenna, E) Embodiments of Multidimensional Dipole Antennas Over FoldedShield, and F) Power Wave Transmission Techniques to Focus WirelesslyDelivered Power at a Receiving Device.

Section A: Example Wireless Power Transmission Systems

FIG. 1 is a high-level block diagram of a wireless power transmissionsystem 100, in accordance with some embodiments. The wireless powertransmission system 100 includes, for example, one or morewireless-power-transmitting devices 102 and one or morewireless-power-receiving devices 120 (FIG. 1 depicts onewireless-power-transmitting device 102 and one wireless-power-receivingdevice 102 for ease of illustration and discussion). In someembodiments, each wireless-power-receiving device 102 includes arespective electronic device 122 (FIG. 2B) and appropriate circuitry forreceiving and using wireless power waves (e.g., antennas 252 and powerharvesting circuitry 256). For example, the appropriate circuitry may becoupled to and/or embedded in the electronic device 122, therebyenabling the device 122 to be charged using wirelessly-delivered powerwaves. For simplicity, the wireless-power-transmitting device 102 isalso referred to more simply as a transmitter 102, and thewireless-power-receiving device 120 is also referred to more simply as areceiver 120.

An example transmitter 102 includes one or more antenna arrays 110-1,110-2, . . . 110-n. Further, each antenna array 110 includes a pluralityof antenna groups 114-1, 114-2, . . . 114-n, where each antenna group114 includes a plurality of antennas 112. The number of antennas shownin each of the plurality of antenna groups 114-1, 114-2, . . . 114-n ismerely one example configuration. As shown, the plurality of antennagroups 114-1, 114-2, . . . 114-n are spaced-apart by distances (D¹ andD²), which may be the same or different distances. Antennas 112 withineach of the antenna groups 114 are configured to transmit (e.g.,radiate) electromagnetic power transmission waves (e.g., electromagneticwaves 116-A, 116-B, and 116-C) to a focal point (e.g., F¹ or F²). Insome embodiments, antennas 112 from one or more antenna groups 114transmit electromagnetic waves to a first focal point (F¹) whileantennas 112 from one or more other antenna groups 114 transmitelectromagnetic waves to a second focal point (F²) that is further fromthe antenna array 110 relative to a location of the first focal point(F¹). In this way, the transmitter diminishes defocusing effects. As aresult, the transmitter 102 is able to transmit electromagnetic waves incompliance with governing regulations set by various agencies around theworld (e.g., the Federal Communications Commission (FCC) in the UnitedStates). Governing regulations are discussed in further detail belowwith reference to FIGS. 17-20.

Furthermore, depending on values of particular transmissioncharacteristics (e.g., phase, amplitude, gain, polarization, frequency,etc.) of the electromagnetic waves transmitted by antennas 112 in thevarious antenna groups 114, some of the electromagnetic waves“constructively interfere” at a focal point while some of theelectromagnetic waves “destructively interfere” at (or around) a focalpoint. To provide some context, constructive interference ofelectromagnetic waves (e.g., radio frequency waves) typically occurswhen two or more electromagnetic waves 116 are in phase with each otherand converge into a combined wave such that an amplitude of the combinedwave is greater than amplitude of a single one of the electromagneticwaves. For example, the positive and negative peaks of sinusoidalwaveforms arriving at a location from multiple antennas “add together”to create larger positive and negative peaks. In some embodiments, afocal point is a point in a transmission field to which antennas aretransmitting power waves to thereby cause constructive interference ofelectromagnetic waves at or very close to (e.g., within 0.1 wavelengthof a frequency of the EM waves) the focal point. In contrast,destructive interference of electromagnetic waves occurs when two ormore electromagnetic waves are out of phase and converge into a combinedwave such that the amplitude of the combined wave is less than theamplitude of a single one of the electromagnetic waves. For example, theelectromagnetic waves “cancel each other out,” thereby diminishing theamount of energy concentrated at a location in the transmission field.In some embodiments, destructive interference is used to generate anegligible amount of energy or “null” at locations within thetransmission field that are outside of the target focal points (e.g., byat least 1 wavelength of distance away from each respective focalpoint).

In some embodiments, values for transmission characteristics of theelectromagnetic waves transmitted by antennas 112-6 to 112-8 in a firstgroup 114-1 are the same as values for transmission characteristics ofthe electromagnetic waves transmitted by antennas 112-4, 112-5 in asecond group 114-2 and different from values for transmissioncharacteristics of the electromagnetic waves transmitted by antennas112-1 to 112-3 in a third group 114-n. Alternatively, in someembodiments, the values for transmission characteristics of theelectromagnetic waves transmitted by the antennas in each respectivegroup are different, at least partially. In certain embodiments orcircumstances, some of the transmission characteristics used withinantenna groups may also vary (e.g., amplitude settings may by the samefor antennas within an antenna group, but phase settings may vary).Values for transmission characteristics are discussed in further detailbelow with reference to FIGS. 17-20.

FIG. 2A is a block diagram illustrating a representative transmitterdevice 102 (also sometimes referred to interchangeably herein as atransmitter 102 and a wireless-power-transmitting device 102) inaccordance with some embodiments. The transmitter device 102 includesone or more processing units 204 (e.g., CPUs, ASICs, FPGAs,microprocessors, and the like), memory 206, one or more antenna arrays110, and one or more communication buses 208 for interconnecting thesecomponents (sometimes called a chipset). Further, the transmitter device102 may include one or more communication components 212, one or moresensors 214, one or more power amplifiers 216, and power feedingcircuitry 218. In some embodiments, the transmitter device 102 furtherincludes a location detection device, such as a GPS (global positioningsatellite) or other geo-location receiver, for determining the locationof the transmitter device 102. The one or more processing units 204 aresometimes referred to herein as “processors” or “controllers.”

In some embodiments, a single processor 204 executes software modulesfor controlling multiple transmitters 102. In some embodiments, a singletransmitter 102 includes multiple processors 204, such as one or moretransmitter processors (configured to, e.g., control transmission ofsignals by one or more antenna arrays 110), one or more communicationscomponent processors (configured to, e.g., control communicationstransmitted by communications component 212 and/or receivecommunications by way of communications component 212) and/or one ormore sensor processors (configured to, e.g., control operation oftransmitter sensor 214 and/or receive output from transmitter sensor214). Furthermore, a single transmitter 102 may be configured to controlone or more antenna arrays 110.

The one or more antenna arrays 110 are configured to transmitelectromagnetic waves to one or more focal points (e.g., F¹ and F², FIG.1), depending on instructions received from the one or more processingunits 204. Each of the one or more antenna arrays 110 includes aplurality of antennas arranged in a plurality of antenna groups, asexplained above with reference to FIG. 1. Various antenna arrayconfigurations and structural antenna designs are provided below.

The one or more communication components 212 (e.g., also referred to as“communication radios,” or simply “radios”) enable communication betweenthe transmitter 102 and other devices and networks. In some embodiments,the one or more communication component 212 include, e.g., hardwarecapable of data communications using any of a variety of wirelessprotocols (e.g., IEEE 802.15.4, Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave,Bluetooth Smart, ISA100.11a, WirelessHART, MiWi, etc.) wired protocols(e.g., Ethernet, HomePlug, etc.), and/or any other suitablecommunication protocol, including communication protocols not yetdeveloped as of the filing date of this document.

In various embodiments, the one or more sensors 214 include but are notlimited to one or more: thermal radiation sensors, ambient temperaturesensors, humidity sensors, IR sensors, occupancy sensors (e.g., RFIDsensors), ambient light sensors, pressure sensors, motion detectors,accelerometers, and/or gyroscopes.

The one or more power amplifiers 216 may be coupled with a power supply(not shown), and a respective power amplifier 216 draws energy from thepower supply to provide electromagnetic waves to one or more of theantenna array(s) 110. Moreover, the respective power amplifier 216 maybe coupled with the power feeding circuitry 218, which is configured togenerate a suitable electromagnetic wave and provide thatelectromagnetic wave to the one or more power amplifier 216, where atleast one power amplifier 216 in turn provides the electromagnetic waveto at least one antenna array 110. In some embodiments, the powerfeeding circuitry 218 includes an oscillator and/or a frequencymodulator that is used to generate the electromagnetic wave so that itis appropriate for transmission (e.g., the electromagnetic wave has anappropriate power level, phase, frequency, etc. to ensure that a maximumamount of energy is transferred from the transmitter 102 to the receiver120). Further, the power feeding circuitry 218 may include a combinerand one or more additional components to facilitate transmission ofelectromagnetic waves from antennas of the one or more antenna arrays.

Further, the one or more processors 204 may send an instruction to theone or more power amplifiers 216 that causes at least some of the one ormore power amplifiers 216 to feed one or more electromagnetic signals toone or more of the antenna array(s) 110, e.g., based on the location ofthe receiver. Additionally, the transmitter 102 may include a switchthat switchably couples the one or more power amplifiers 216 to arespective group (or groups) 114 of a respective antenna array (orantenna arrays) 110.

The memory 206 includes high-speed random access memory, such as DRAM,SRAM, DDR SRAM, or other random access solid state memory devices; and,optionally, includes non-volatile memory, such as one or more magneticdisk storage devices, one or more optical disk storage devices, one ormore flash memory devices, or one or more other non-volatile solid statestorage devices. The memory 206, or alternatively the non-volatilememory within memory 206, includes a non-transitory computer-readablestorage medium. In some embodiments, the memory 206, or thenon-transitory computer-readable storage medium of the memory 206,stores the following programs, modules, and data structures, or a subsetor superset thereof:

-   operating logic 220 including procedures for handling various basic    system services and for performing hardware dependent tasks;-   communication module 222 for coupling to and/or communicating with    remote devices (e.g., remote sensors, transmitters, receivers,    servers, mapping memories, etc.) in conjunction with communication    component(s) 212;-   sensor module 224 for obtaining and processing sensor data (e.g., in    conjunction with sensor(s) 214) to, for example, determine the    presence, velocity, and/or positioning of objects in the vicinity of    the transmitter 102;-   focal point selection module 226 for determining where to respective    focal point(s) to use for transmission of electromagnetic waves    based on information obtained by the communication module 222, the    sensor module 224, and/or the antenna array(s) 110;-   power wave generating module 228 for generating and transmitting    (e.g., in conjunction with antenna(s) 110) electromagnetic waves,    including but not limited to, forming pocket(s) of energy at given    locations (e.g., at one or more focal points). In some embodiments,    the power wave generating module 228 also includes or is associated    with a characteristic selection module 244 that is used to select    values for transmission characteristics of transmitted    electromagnetic waves;-   antenna tuning module 230 for tuning (e.g., up-tuning and    down-tuning) antenna elements of the antenna array(s) 110, in    conjunction with one or more electrical switches (e.g., switches    1120, 1122, 1124, and 1126, FIG. 11A); and-   database 232, including but not limited to:    -   sensor information 234 for storing and managing data received,        detected, and/or transmitted by one or more sensors (e.g.,        sensors 114 and/or one or more remote sensors);    -   device settings 236 for storing operational settings for the        transmitter 102 and/or one or more remote devices (e.g., sets of        characteristics for the transmitter);    -   communication protocol information 238 for storing and managing        protocol information for one or more protocols (e.g., custom or        standard wireless protocols, such as ZigBee, Z-Wave, etc.,        and/or custom or standard wired protocols, such as Ethernet);    -   beam lookup table(s) 240 for storing values of transmission        characteristics information that are selected based on a        receiver's location (e.g., storing values for various waveform        characteristics); and    -   mapping data 242 for storing and managing mapping data (e.g.,        mapping one or more transmission fields, and zones within        respective transmission fields).

In some embodiments, the characteristic selection module 244 of theelectromagnetic wave generating module 228 may be used to select valuesfor particular transmission characteristics (also referred to herein aswaveform characteristics) of transmitted electromagnetic waves. Thewaveform characteristics may include phase, gain, amplitude, direction,frequency, and polarization, and the selection module 244 may selectparticular values for each of those characteristics. In someembodiments, the selection module 244 may select the waveformcharacteristics based on information received from the receiver device120 (or the electronic device 122), and/or using information stored inthe beam lookup tables 240. In some embodiments, the selection module244 and the antenna tuning module 230 work in tandem to selectparticular values for each of the characteristics. In some embodiments,many of the components described with reference to FIG. 2A areimplemented on single integrated circuit, such as that described indetail in U.S. patent application Ser. No. 15/963,959, and thedescriptions of this single integrated circuit (provided with referenceto FIGS. 1A-1C in U.S. patent application Ser. No. 15/963,959) areincorporated by reference herein. Any of the antenna arrays orindividual antennas described herein may be controlled by this singleintegrated circuit, which may also implement and control the powertransmission techniques that are discussed below.

Each of the above-identified elements (e.g., modules stored in memory206 of the transmitter 102) is optionally stored in one or more of thepreviously mentioned memory devices, and corresponds to a set ofinstructions for performing the function(s) described above. The aboveidentified modules or programs (e.g., sets of instructions) need not beimplemented as separate software programs, procedures, or modules, andthus various subsets of these modules are optionally combined orotherwise rearranged in various embodiments. In some embodiments, thememory 206, optionally, stores a subset of the modules and datastructures identified above. Furthermore, the memory 206, optionally,stores additional modules and data structures not described above.

FIG. 2B is a block diagram illustrating a representative receiver device120 (also referred to herein as a receiver 120 or a wireless powerreceiver/wireless-power-receiving device 120) in accordance with someembodiments. In some embodiments, the receiver device 120 includes oneor more processing units 250 (e.g., CPUs, ASICs, FPGAs, microprocessors,and the like), one or more antenna 252, one or more communicationcomponents 254, memory 255, power harvesting circuitry 256, and one ormore communication buses 251 for interconnecting these components(sometimes called a chipset). In some embodiments, the receiver device120 includes one or more sensors 258. In some embodiments, the receiverdevice 120 includes an energy storage device 260 for storing energyharvested via the power harvesting circuitry 256. In variousembodiments, the energy storage device 260 includes one or morebatteries, one or more capacitors, one or more inductors, and the like.The one or more processing units 250 are sometimes referred to herein as“processors” or “controllers.” The receiver 120 may be internally orexternally connected to an electronic device 122 via a connection (e.g.,a bus) 261. A combination of the receiver 120 and the electronic device122 is sometimes referred to herein as a “wireless-power-receivingdevice.”

In some embodiments, the power harvesting circuitry 256 includes one ormore rectifying circuits and/or one or more power converters. In someembodiments, the power harvesting circuitry 256 includes one or morecomponents (e.g., a power converter) configured to convert energy fromelectromagnetic waves to electrical energy (e.g., electricity). In someembodiments, the power harvesting circuitry 256 is further configured tosupply power to a coupled electronic device 122, such as a laptop orphone. In some embodiments, supplying power to a coupled electronicdevice 112 includes translating electrical energy from an AC form to aDC form (e.g., usable by the electronic device 122).

In some embodiments, the receiver device 120 includes one or more outputdevices such as one or more indicator lights, a sound card, a speaker, asmall display for displaying textual information and error codes, etc.(in some embodiments, the receiver device 120 sends information fordisplay at an output device of an associated electronic device). In someembodiments, the receiver device 120 includes a location detectiondevice, such as a GPS (global positioning satellite) or othergeo-location receiver, for determining the location of the receiverdevice 120.

In various embodiments, the one or more sensors 258 include one or morethermal radiation sensors, ambient temperature sensors, humiditysensors, IR sensors, occupancy sensors (e.g., RFID sensors), ambientlight sensors, motion detectors, accelerometers, and/or gyroscopes.

The optional communication component(s) 254 enable communication betweenthe receiver 120 and other devices and networks. In some embodiments,the communication component(s) 254 include, e.g., hardware capable ofdata communications using any of a variety of custom or standardwireless protocols (e.g., IEEE 802.15.4, Wi-Fi, ZigBee, 6LoWPAN, Thread,Z-Wave, Bluetooth Smart, ISA100.11a, WirelessHART, MiWi, etc.) custom orstandard wired protocols (e.g., Ethernet, HomePlug, etc.), and/or anyother suitable communication protocol, including communication protocolsnot yet developed as of the filing date of this document. In someembodiments, the receiver 120 may utilize a built-in communicationcomponent (e.g., a Bluetooth radio) of the electronic device 122 withwhich the receiver 120 is coupled, and therefore, in these embodiments,the receiver 120 may not include its own communication component.

The memory 255 includes high-speed random access memory, such as DRAM,SRAM, DDR SRAM, or other random access solid state memory devices; and,optionally, includes non-volatile memory, such as one or more magneticdisk storage devices, one or more optical disk storage devices, one ormore flash memory devices, or one or more other non-volatile solid statestorage devices. The memory 255, or alternatively the non-volatilememory within memory 255, includes a non-transitory computer-readablestorage medium. In some embodiments, the memory 255, or thenon-transitory computer-readable storage medium of the memory 255,stores the following programs, modules, and data structures, or a subsetor superset thereof:

-   operating logic 262 including procedures for handling various basic    system services and for performing hardware dependent tasks;-   communication module 263 for coupling to and/or communicating with    remote devices (e.g., remote sensors, transmitters, receivers,    servers, electronic devices, mapping memories, etc.) in conjunction    with communication component(s) 254;-   sensor module 264 for obtaining and processing sensor data (e.g., in    conjunction with sensor(s) 258) to, for example, determine the    presence, velocity, and/or positioning of the receiver 120, a    transmitter 102, or an object in the vicinity of the receiver 120;-   power receiving module 266 for receiving (e.g., in conjunction with    antenna(s) 252 and/or power harvesting circuitry 256)    electromagnetic waves and optionally converting (e.g., in    conjunction with power harvesting circuitry 256) the electromagnetic    waves into usable energy (e.g., to direct current); transferring the    energy to a coupled electronic device (e.g., an electronic device    122); and optionally storing the energy (e.g., in conjunction with    energy storage device 260)-   usable power determining module 268 for determining (in conjunction    with operation of the power receiving module 266) an amount of    usable power received by the receiver 120 based on energy extracted    from electromagnetic waves; and-   database 270, including but not limited to:    -   sensor information 272 for storing and managing data received,        detected, and/or transmitted by one or more sensors (e.g.,        sensors 258 and/or one or more remote sensors);    -   device settings 274 for storing operational settings for the        receiver 120, a coupled electronic device (e.g., an electronic        device 122), and/or one or more remote devices; and    -   communication protocol information 276 for storing and managing        protocol information for one or more protocols (e.g., custom or        standard wireless protocols, such as ZigBee, Z-Wave, etc.,        and/or custom or standard wired protocols, such as Ethernet).

In some embodiments, the usable power receiving module 268 communicatesthe amount of usable power to the communication module 263, whichcommunicates (e.g., in conjunction with communication component(s) 254)the amount of usable power to other remote devices (e.g., transmitter102, FIG. 2A). Moreover, in some embodiments, the usable power receivingmodule 268 communicates the amount of usable power to the database 270(e.g., the database 270 stores the amount of usable power derived fromelectromagnetic waves). In some embodiments, the usable power receivingmodule 268 instructs the communication module 263 to transmit distincttransmissions to the remote devices (e.g., a first communication signalthat indicates a first amount of usable power received by the receiver120 and a second communication signal that indicates a second amount ofusable power received by the receiver 120).

Each of the above identified elements (e.g., modules stored in memory255 of the receiver 120) is optionally stored in one or more of thepreviously mentioned memory devices, and corresponds to a set ofinstructions for performing the function(s) described above. The aboveidentified modules or programs (e.g., sets of instructions) need not beimplemented as separate software programs, procedures, or modules, andthus various subsets of these modules are optionally combined orotherwise rearranged in various embodiments. In some embodiments, thememory 255, optionally, stores a subset of the modules and datastructures identified above. Furthermore, the memory 255, optionally,stores additional modules and data structures not described above.

Section B: Example Antenna Array Configurations, Including ExampleAntenna Arrays with Co-Polarized Antenna Groups that ProducePerpendicularly Oriented Radiation Patterns

FIG. 3A illustrates an example duplet 300 of co-polarized antennas 302,304 that produce perpendicularly-oriented radiation patterns, inaccordance with some embodiments. As shown, the antenna duplet 300includes a first antenna 302 and a second antenna 304 spaced-apart by adistance (D) that is determined relative to an operating frequency (f)and associated wavelength (λ) of the antenna duplet 300. The distancebetween the first antenna 302 and the second antenna 304 can range fromapproximately 1/30λ (or less) to λ/2. In certain embodiments, the rangecan be larger, such as 1/50λ to λ/2 or may be smaller, such as 1/10λ toλ/2. The antenna duplet 300 may be part of an antenna array (e.g.,antenna array 110, FIG. 1) that includes a plurality of antenna duplets(e.g., duplets 702 and 704, FIG. 7A). Although not shown in FIG. 3A, theantenna duplet 300 may be positioned on a metal reflector (which asdiscussed in more detail below does not alter the respectivepolarizations and/or radiation patterns of the antennas 302, 304).

Densely populated antenna arrays typically suffer from undesired mutualcoupling between neighboring antenna elements, which limits the antennaarray's radiation efficiency and its beamforming capabilities (thisproblem is particularly acute when the antenna elements are placedclosed together and when the antenna elements are miniaturized). “Mutualcoupling” refers to energy being absorbed by one antenna when anothernearby antenna is radiating. When individual antennas are miniaturized,a certain amount of radiation efficiency is also sacrificed and,therefore, mutual coupling effects for miniaturized antennas furtherdegrade an individual antenna's radiation efficiency making itdifficult, if not impossible, for miniaturized antennas to transfersufficient energy to a receiver that is located at a non-trivialdistance away from the individual antenna (e.g., one-three feet awayfrom the individual antenna).

By pairing together antennas that exhibit specific properties (e.g.,co-polarization and perpendicularly-oriented radiation patterns), it hasbeen discovered that mutual coupling between neighboring antennaelements is reduced substantially, such that mutual coupling betweenneighboring antenna elements is negligible (e.g., mutual coupling may bereduced to less than −20 dB, and, in some instances, to below −25 dB).In light of this discovery, the antenna array 110 (which includes pairsof antennas that exhibit these specific properties) can be miniaturized(e.g., to include smaller antennas that are placed closer together),without further impacting the array's radiation efficiency. Althoughminiaturized antennas are the primary examples utilized in the presentdescription, the principles also apply to larger resonant antennas, suchas half-wavelength antennas, possessing the equivalent co-polarizationand radiation pattern orthogonality properties.

To provide some context for the distance (D), in some embodiments, thefirst and second antennas have operating frequencies that range from 400MHz to 60 GHz. As an example, if the first and second antennas areoperating at 915 MHz (e.g., radiating electromagnetic signals having afrequency of 915 MHz), then the distance (D) can range fromapproximately 1 cm to 16 cm when the distance (D) ranges fromapproximately 1/30λ to λ/2, respectively.

The various antenna types and combinations of antennas are discussed indetail below. Further, it is noted that an “antenna duplet” may be anexample one of the plurality of antenna groups 114-1, . . . 114-n (FIG.1).

FIGS. 3B-1 and 3B-2 illustrate radiation patterns generated by the firstantenna 302 (which includes ports 306-1 and 306-2, each respectivelycoupled with a radiating element 303) and the second antenna 304 (whichincludes port 306-3 that is coupled with a radiating element 305),respectively, in accordance with some embodiments. With reference toFIG. 3B-1, the first antenna 302 is configured to generate a firstradiation pattern 310 polarized in a first direction (e.g., aligned withthe X-axis), e.g., in response to electromagnetic waves being fed to thefirst antenna 302 (e.g., via one or more of the power amplifier(s) 216,FIG. 2A). As shown, the first radiation pattern 310 has a higherconcentration of EM energy produced along the Z-axis and the X-axis (andhas a radiation null along the Y-axis) and forms an overall torus shape.Now, with reference to FIG. 3B-2, the second antenna 304 is configuredto generate a second radiation pattern 312 also polarized in the firstdirection, e.g., in response to electromagnetic waves being fed to thesecond antenna 304. Thus, the first and second antennas 302, 304 areboth polarized in the first direction (e.g., both aligned with theX-axis), and therefore the two antennas are said to be “co-polarized.”It is noted that a radiation pattern's orientation may be changed if,say, the antenna is rotated (e.g., rotated 90 degrees). Accordingly,orientations of the first and second antennas 302, 304 relative to eachother are respectively selected to ensure that the antenna radiationpatterns will be perpendicularly oriented relative to one another.

Further, the second radiation pattern 312 has a higher concentration ofEM energy produced along the Z-axis and the Y-axis, and has a radiationnull along the X-axis. Accordingly, while the first and second radiationpatterns 310, 312 both form an overall torus shape, they areperpendicularly-oriented relative to one another. Stated another away,the first and second radiation patterns 310, 312 share a common axiswith high concentrations of EM energy (e.g., both main lobes/beams inthe first and second radiation patterns 310/312 travel along the Z-axisthat moves away from a top surface of the antennas 302, 304), and alsohave high concentrations of EM energy on non-shared axes that are eachorthogonal to the one shared axis. Because the respective non-sharedaxes are also perpendicular to one another, the first and secondradiation patterns 310, 312 (e.g., their respective main lobes/beams)are said to be perpendicularly oriented relative to one another along atleast one axis.

In such an arrangement, the first antenna 304 creates a radiation nullalong its Y-axis, which is the direction of maximum radiation of thesecond antenna 304. Therefore, the pair of adjacent antennas does notcommunicate, e.g., if the second antenna 304 is deemed a transmitter,then the first antenna 302 is arranged and configured relative to thesecond antenna 304 such that the first antenna 302 does not receiveanything (or if it does receive some electromagnetic energy, itsnegligible. Thus, any mutual coupling between the two antennas 302, 304in this configuration is minimal. Thus, the first and second antennas302, 304 are configured to generate radiation patterns perpendicular toeach other while also having electric field polarizations parallel toeach other.

The discussion above can be summarized in the following way: the firstradiation pattern 310 and the second radiation pattern 312 are bothpolarized along a first axis (e.g., the X-axis). Further, the firstradiation pattern 310 is almost omnidirectional in the plane along thepolarization direction and the second radiation pattern 312 is almostomnidirectional in a plane orthogonal to the first radiation pattern 310and to the direction of the polarization, or interchangeably the firstradiation pattern 310 is almost omnidirectional in a plane perpendicularto the polarization and the second radiation pattern 312 is almostomnidirectional in a plane co-planar with the polarization.

FIG. 3C illustrates a resulting radiation pattern 320 in accordance withsome embodiments. The resulting radiation pattern 320 is produced whenthe first and second antennas 302, 304 are radiating together. As shown,the resulting radiation pattern 320 does not have an overall torus shapebut instead has a spherical shape. Further, the resulting radiationpattern 320 is polarized in the first direction (e.g., aligned with theX-axis), has most of its radiation focused in the forward direction(e.g., along the Z-axis), and has very little backwards radiation. It isnoted that a total electric field vector of the resulting radiationpattern 320 has a magnitude equal to the sum of the magnitudes of theindividual electric fields of the first and second antennas 302, 304 inthe first direction, which contributes to the high gain for the antennaduplet. In some instances, the antenna duplet 300 is able to obtain aradiation efficiency of approximately 70%.

FIG. 3D illustrates a cross-sectional view 330 of the resultingradiation pattern 320 (taken along the X-Z plane shown in FIG. 3C), inaccordance with some embodiments. The cross-sectional view 330 includesgain along the X-axis (Phi) and also gain along the Z-axis (Theta). Asshown, the gain along the Z-axis (Theta) has an approximate value of3.3605 dB at a first indicated marker point, m1, and has an approximatevalue of −11.7488 at a second indicated marker point, m2, resulting inan overall front-to-back ratio of approximately 15.1093 dB (e.g., thedifference between gain at the indicated marker points, m1 and m2, inFIG. 3D). The “front-to-back ratio” compares antenna gain in a specifieddirection, e.g., usually the direction of maximum gain, to the gain in adirection 180° from the specified direction. A positive front-to-backratio indicates that more energy is radiated in the specified directionrelative to an amount of energy radiated in the opposite direction. Withthis in mind, a front-to-back ratio of approximately 15 dB indicatesthat most of the radiated energy in the resulting radiation pattern 320travelled away from the antenna duplet 300 along the Z-Axis (Theta),whereas a negligible amount travelled in the opposite direction (the“backwards” direction). This positive front-to-back ratio can beattributed to the first and second antennas 302, 304 having electricfield vectors in the backwards direction that are anti-parallel (e.g.,parallel along a common axis but moving in opposing directions alongthat common axis).

Furthermore, the gain along the X-axis (Phi) is fairly uniform (althoughnot shown, the gain along the Y-axis is also fairly uniform). Theresulting radiation pattern 320 achieves its spherical shape due to theuniform nature of the gains along the X-axis and Y-axis, and the lack ofmutual coupling (discussed below) between the transmitting antennas 302,304.

FIG. 3E is a diagram 340 that illustrates mutual coupling (curve 342)between the first and second antennas 302, 304, in accordance with someembodiments. In some embodiments, mutual coupling (i.e., the “couplingeffect”) is measured between respective ports/feeds of the first andsecond antennas 302, 304, and the coupling effect indicates an amount ofradiated electromagnetic energy that is absorbed by, e.g., the antenna304 when the antenna 302 is radiating electromagnetic signals (and viceversa). For example, the first antenna 302 has ports 1 and 2 (depictedas ports 306-1 and 306-2 in FIG. 3A) and the second antenna 304 has atleast port 3 (depicted as portion 306-3 in FIG. 3A), and in thisexample, curve 342 in the diagram 340 illustrates that the couplingeffect between ports 2 and 3 of the first and second antennas 302, 304,respectively, peaks at −18 dB when both antennas are radiatingelectromagnetic waves at approximately 915 MHz. As compared to someconventional antenna array designs, a coupling effect of −18 dB is verylow, as certain conventional antenna arrays designs have couplingeffects of 0.5 dB, which negatively impacts radiation efficiency (aswell as negative heat absorption effects at the antennas in the array)that limit effectiveness of these array designs for wireless powerapplications, especially for implementations that require very smallantennas. The other curves 343, 344, 345, and 346 show measurements ofcoupling effects between each of ports 3, 3; 2, 1; 2, 2; and 1, 1,respectively.

It is noted that the X-axis in the diagram 340 corresponds to anoperating frequency of the antennas 302, 304, and the Y-axis correspondsto an amount of electromagnetic energy measured in decibels (dB). Asshown, the coupling effect is negligible below approximately 900 MHz andabove 930 MHz because the antennas 302, 304 are not tuned to radiateelectromagnetic energy at those frequencies and, thus, feeding insignals with those frequencies does result in a low coupling effectbecause the signals are almost completely reflected back, therefore theamount of power entering the antennas is negligible: the amount ofradiated energy is also very low, and hence, so is the coupling betweenthe antennas. The important physics happen at the mutual matching bandof the antennas, in the operating frequencies around 915 MHz, where thematching is good, and therefore reflected power is minimal the signalproceeds into the antennas), power is efficiently radiated by theantennas but the coupling remains at the level of −20 dB or smaller,which is equally negligible. This is the resultant operation of thepresent physical principle and corresponding embodiments of thisinvention.

An additional feature that is possible by pairing together co-polarizedantennas that produce perpendicularly oriented radiation patterns iscomplete reversal of beam direction. In some embodiments, an electronicphase shift of 180° in any one of the two antennas (but not in both),reverses the direction of the corresponding electric field vector (e.g.,reversing the regions of space where the fields add constructively orsubtract). Accordingly, embodiments of transmitter 102 that includeduplets of antennas as discussed herein (e.g., the duplets of FIG. 6A)can control whether the high-gain region is forward (low-gain regionbackward) or backward (low-gain region forward). This is electronic beamcomplete reversal, and is an additional unique feature exhibited by thepairing together of co-polarized antennas that produce perpendicularradiation patterns. Complete reversal of beam direction is alsodiscussed in more detail below in reference to FIGS. 9D-9E.

FIGS. 4A-4E are used to illustrate certain detrimental effects caused bymutual coupling in antenna arrays using conventional antennas. Forexample, FIGS. 4B-1 and 4B-2 illustrate radiation patterns generated byan antenna duplet that includes first and second patch antennas (e.g.,instances of patch antenna 400, FIG. 4A, which includes respective ports401-2 and 401-4). As shown, the first patch antenna generates a firstradiation pattern 410, polarized in a first direction, and has a higherconcentration of EM energy produced along the Z-axis and the X-axis (andhas a radiation null along the Y-axis) and has a peak gain of 1.58 dB.Further, the second patch antenna generates a second radiation pattern412, polarized in the first direction, and also has a higherconcentration of EM energy produced along the Z-axis and the X-axis (andhas a radiation null along the Y-axis) and has a peak gain of 1.57 dB.Thus, the first and second radiation patterns 410, 412 are oriented inparallel to one another. The parallelism of the first and secondradiation patterns 410, 412 causes substantial mutual coupling effectsbetween the two patch antennas, especially when they are placed closetogether (e.g., less than ½ of a wavelength of an operating frequency ofthe patch antennas).

The resulting radiation pattern 420 shown in FIG. 4C is a combination ofthe first and second radiation patterns 410, 412. The resultingradiation pattern 420 is polarized in the first direction, has a higherconcentration of EM energy produced along the Z-axis and the X-axis (andhas a radiation null along the Y-axis), and forms an overall torus shapehaving a peak gain of 1.95 dB.

FIG. 4D illustrates a cross-sectional view of the resulting radiationpattern 420 (taken along the X-Z plane shown in FIG. 4C), in accordancewith some embodiments. The cross-sectional view 430 includes gain alongthe X-axis (Phi) and also gain along the Z-Axis (Theta). As shown, thegain along the Z-Axis (Theta) has a front-to-back ratio of approximately0.5 dB, which indicates that approximately equal amounts of energyradiates away from and towards the antenna duplet along the Z-Axis(Theta) (i.e., backwards radiation substantially equals forwardsradiation). This result is expected as the resulting radiation pattern420 forms an overall torus shape, as was discussed above. Further, withreference to FIG. 4E, curve S₄₂ of the diagram 440 illustrates a mutualcoupling between the first and second patch antennas (measured between arespective port 401-4 of the first patch antenna and a respective port401-2 of the second patch antenna) peaks at about −4 dB when bothantennas are radiating electromagnetic waves at a center frequency ofapproximately 925 MHz (measured between port 4 and 2 of the antenna,respectively). Negative coupling effects, such as −4 dB, can causedamaging effects on radiation efficiency (as well as negative heatabsorption effects at the antennas in the array) that limiteffectiveness of the first and second patch antennas for wireless powerapplications. The other curves S₂₂ and S₄₄ show measurements of couplingeffects between ports 2 (e.g., a respective port 401-2 of the firstpatch antenna) and 2 (e.g., a respective port 401-2 of the second patchantenna); and 4 (e.g., a respective port 401-4 of the first patchantenna) and 4 (e.g., a respective port 401-4 of the second patchantenna), respectively.

Accordingly, the results shown in FIGS. 4C-4E highlight the limitationsof conventional antenna arrays. Antenna duplets (e.g., antenna duplet300 described above and others described elsewhere herein) that exhibitco-polarization and perpendicular radiation patterns remedy the lowradiation efficiency and poor front-to-back ratio exhibited by thepairing of conventional antennas explained with reference to FIGS.4C-4E, and achieve other benefits (e.g., the ability to completelyreverse beam direction).

FIG. 5 illustrates an example antenna duplet 500 in accordance with someembodiments. The antenna duplet 500 is an example of the antenna duplet300 (FIG. 3A). In other words, the antenna duplet 500 includesco-polarized antennas that produce perpendicularly-oriented radiationpatterns. In this particular example, the first antenna 502 is aninstance of the patch antenna 400 (FIG. 4A) that includes multiple feeds503-1, 503-2 and a radiating element 504 (e.g., a metal patch). Thefirst antenna 502 is configured to generate a radiation pattern similarto the radiation pattern shown in FIG. 3B-1 (the first antenna 502 isillustrated as being semi-transparent for ease of illustration anddiscussion). In contrast, the second antenna 512 is a drop-in stampedantenna (which is the first embodiment of a drop-in antenna 1000,described in more detail below in reference to FIG. 10A) that includesat least one feed/port 513 and radiating elements 514-1, 514-2. Thesecond antenna 512 is configured to generate a radiation pattern similarto the radiation pattern shown in FIG. 3B-2. In some embodiments, thefirst and second antennas 502, 512 are fixed to a reflector 520 (e.g., ametal plate). In this configuration, the antenna duplet 500 can create aresulting radiation pattern similar (if not the same) to the resultingradiation pattern 320 shown in FIG. 3C. The second antenna 512 isdiscussed in further detail below with reference to FIGS. 10A-10F.

FIG. 6A illustrates an example antenna duplet 600 in accordance withsome embodiments. The antenna duplet 600 is an example of the antennaduplet 300 (FIG. 3A). In other words, the antenna duplet 600 includesco-polarized antennas that produce perpendicularly-oriented radiationpatterns. In this particular example, the first antenna 602 is a drop-intunable patch antenna (which is the third embodiment of a drop-inantenna, and is described in more detail in reference to FIG. 12A) thatincludes at least one port 603 (port 1) and a radiating element 604(e.g., a metal patch) (the first antenna 602 is illustrated as beingsemi-transparent for ease of illustration and discussion). The secondantenna 612 is a drop-in printed antenna (which is the second embodimentof a drop-in antenna, and is described in more detail in reference toFIG. 11A) that includes at least one port (port 2) and radiatingelements 614-1, 614-2. The first and second antennas 602, 612 are fixedto a reflector 620 (e.g., a metal plate), which is optional. The firstand second antennas 602 and 612 are discussed in further detail belowwith reference to FIGS. 12A-12D and 11A-11C-3, respectively.

FIGS. 6B-1 and 6B-2 illustrate radiation patterns generated by the firstand second antennas 602, 614, respectively, in accordance with someembodiments. With reference to FIG. 6B-1, the first antenna 602 isconfigured to generate a first radiation pattern 620 polarized in afirst direction (e.g., aligned with the X-axis). Further, the firstradiation pattern 620 has a higher concentration of EM energy producedalong the Z-axis and the X-axis (and has a radiation null along theY-axis) and forms an overall torus shape having a peak gain ofapproximately 0.505 dB. With reference to FIG. 6B-2, the second antenna612 is configured to generate a second radiation pattern 622 alsopolarized in the first direction (i.e., the first and second antennas602, 612 are co-polarized). Further, the second radiation pattern 622has a higher concentration of EM energy produced along the Z-axis andthe Y-axis (and has a radiation null along the X-axis) and forms anoverall torus shape having a peak gain of 0.247 dB. Thus, while thefirst and second radiation patterns 620, 622 both form an overall torusshape, they are perpendicularly-oriented relative to one another.

FIG. 6C illustrates a resulting radiation pattern 630 in accordance withsome embodiments. The resulting radiation pattern 630 is produced whenthe first antenna 602 and the second antenna 612 are radiating together.As shown, the resulting radiation pattern 630 does not have an overalltorus shape but instead has a spherical shape (e.g., similar to a shapeof the resulting radiation pattern 320, FIG. 3C). Further, the resultingradiation pattern 630 is polarized in the first direction (e.g., alignedwith the X-axis) and has a peak gain of 3.11 dB, which is substantiallylarger than the peak gains of the first and second radiation patterns620, 622 individually, and the resulting radiation pattern 420 (FIG.4C). In some instances, the antenna duplet 600 achieves a radiationefficiency of approximately 70%.

FIG. 6D illustrates a cross-sectional view 640 of the resultingradiation pattern 630 (taken along the X-Z plane shown in FIG. 6C), inaccordance with some embodiments. The cross-sectional view 640 includesgain along the X-axis (Phi) and gain along the Z-Axis (Theta). As shown,the gain along the Z-Axis (Theta) has a front-to-back ratio ofapproximately 15 dB.

FIG. 6E is a diagram that illustrates mutual coupling effects betweenthe individual antennas (e.g., antenna 602, 612) of the example antennaduplet depicted in FIG. 6A, in accordance with some embodiments. CurveS₂₁ in the diagram 650 illustrates that mutual coupling (i.e., couplingeffect) between the first and second antennas 602, 612 peaks at −24 dBwhen both antennas are radiating electromagnetic waves at 915 MHz(measured between ports 1 (illustrated as port 603 in FIG. 6A) and 2(illustrated as port 613 in FIG. 6A) of antennas 602 and 612,respectively). Accordingly, the antenna duplet 600 achieves an evenlower coupling than that achieved by the antenna duplet 500. The othercurves S₁₁ and S₂₂ show measurements of coupling effects between ports1, 1; and 2, 2, respectively.

Accordingly, the antenna duplet 600 includes two antennas that generateradiation patterns that are perpendicularly oriented relative to eachother while also having electric field polarizations parallel to eachother. In doing so, the antenna duplet 600 is able reduce mutualcoupling between the two antennas to a negligible amount, while alsomaintaining or improving other radiation metrics (e.g., radiationefficiency of the antenna duplet).

FIGS. 7A-9E illustrate various antenna array configurations using theantenna duplet 600 illustrated in FIG. 6A (and associatedcharacteristics of these various antenna array configurations) inaccordance with some embodiments. It is noted that the antennasillustrated in FIGS. 7A-9E can be various sizes relative to one another,and the example sizes shown in FIGS. 7A-9E are not limiting (e.g., oneantenna in each duplet has a smaller area than the other antenna in theduplet). Furthermore, while the antenna duplet 600 is used as an examplein FIGS. 7A-9E, various other antennas and antenna duplets describedherein could instead be used, along with other co-polarized antennasthat produce perpendicularly-oriented radiation patterns (e.g., any ofthe embodiments of the drop-in antennas).

FIG. 7A illustrates an example quadruplet antenna array 700 inaccordance with some embodiments. The quadruplet antenna array 700includes a first antenna duplet 702 and a second antenna duplet 704collinearly aligned along the Y-axis (e.g., the two antenna duplets areco-axial). The antenna duplets 702, 704 are positioned on a substrate(e.g., reflector 620, FIG. 6A), which is optional. In some embodiments,the first and second antenna duplets 702, 704 are different duplets. Forexample, the first antenna duplet 702 may be the antenna duplet 600while the second antenna duplet 704 may be the antenna duplet 500, orsome other combination of antenna duplets.

In the illustrated example, the first and second antenna duplets 702,704 mirror each other along the X-axis (e.g., the first antenna duplet702 is a mirror image of the second antenna duplet 704, and vice versa).Alternatively, the first and second antenna duplets 702, 704 may bepositioned serially (i.e., each duplet has the same orientation andarrangement as shown in FIG. 9A-1). Alternatively, in some embodiments,the first and second antenna duplets 702, 704 are rotated relative toone another (e.g., the first antenna duplet 702 is rotated 180 degreesrelative to the second antenna duplet 704). The particular arrangementof the first and second antenna duplets 702, 704 is chosen based, atleast in part, on the charging environment (e.g., wireless chargingversus some other application). Accordingly, each particular arrangementcreates different radiation patterns and corresponding metrics/values(e.g., gain, back-to-front ratio, mutual coupling, etc.).

In some embodiments, the serial arrangement in FIG. 19A is chosenbecause the maximum array gain may be obtained without a phase shiftbetween the duplets. In other embodiments, the mirrored array of FIG.19B may be chosen for a completely symmetrical transmitter system, whichcan execute near-field beam focusing with symmetric sets of phase shiftsbetween mirror-symmetric pairs. In yet other embodiments, the rotatedarray of FIG. 19C may be chosen, which requires specific phasedifference between rotated pairs.

Furthermore, antennas in the first antenna duplet 702 are spaced-apartby a distance (D) and antennas in the second antenna duplet 704 arespaced-apart by a distance (D). The two distances (D) can be the samedistance or different distances. In some embodiments, the distance (D)is considerably less than 1λ (which is determined based on a centeroperating frequency of each of the antenna duplets 702, 704), e.g., Dmay be between ½λ to 1/30λ. Such close inter-element spacing is notcurrently feasible for conventional antenna structures (especially forminiaturized antenna structures), as the mutual coupling effectsnegatively impact radiation efficiency, rending these conventionalduplets useful in densely packed antenna arrays.

Additional examples of the inter-element spacing distance (D) areprovided above with reference to FIG. 3A. The first and second antennaduplets 702, 704 are also spaced-apart by a separation distance (S). Theseparation distance (S) may be an example of the distance (D¹) and/orthe distance (D²) (FIG. 1). As shown, the separation distance (S) isgreater than the inter-element spacing distances (D). In someembodiments, however, the separation distance (S) is equal to or lessthan that the inter-element spacing distances (D). In general, theinter-element distance (D) is smaller than the separation distance (S).The separation distance (S) is the minimum acceptable distance where aset of antennas is grouped to form a single multiplet (e.g., duplet,etc.). The separation distance (S) is the distance that separatesadjacent multiplets and therefore is typically greater than theinter-element distance (e.g., if it were smaller, then two multipletswould generally be grouped together, resulting in a single multiplet).

FIG. 7B is a diagram 710 that illustrates mutual coupling between thefirst and second antenna duplets 702, 704, in accordance with someembodiments. Curves 711 and 712 of the diagram 710 illustrate thatmutual coupling between the first and second antenna duplets 702, 704(and the antennas therein) peaks at −27 dB when the duplets' 702, 704antennas are radiating electromagnetic waves at approximately 915 MHz(measured between ports 2 (illustrated as port 613 in FIG. 6A) and 1(illustrated as port 603 in FIG. 6A) in the first antenna duplet 702 andports 4 (illustrated as port 613 in FIG. 6A) and 3 (illustrated as port603 in FIG. 6A) in the second antenna duplet 704). As compared to someconventional antenna array designs, a coupling effect of −27 dB is verylow (essentially negligible), as explained above with reference to FIG.3E. The other curves 713, 714, 715, and 716 show measurements ofcoupling effects between each of ports 1, 1; 2, 2; 3, 3; and 4, 4,respectively.

FIG. 8A illustrates an example quadruplet antenna array 800 inaccordance with some embodiments. It is noted that the antennasillustrated in FIG. 8A can be various sizes relative to one another, andthe sizes shown in FIG. 8A are not meant limiting (e.g., one antenna ineach duplet has a smaller area than the other antenna in the duplet).

The quadruplet antenna array 800 includes a first antenna duplet 802 anda second antenna duplet 804 forming a substantially rectangular array.The antenna duplets 802, 804 are positioned on a substrate (e.g.,reflector 620, FIG. 6A), which is optional. In some embodiments, thefirst and second antenna duplets 802, 804 are different duplets. Forexample, the first antenna duplet 802 may be the antenna duplet 600while the second antenna duplet 804 may be the antenna duplet 500, orsome other combination of antenna duplets.

In the illustrated example, a structure of the first antenna duplet 802mirrors the structure of the second antenna duplet 804 (and vice versa).Moreover, the first and second antenna duplets 802, 804 are offset fromeach other along the X-axis, as opposed to being collinearly alignedalong the Y-axis, as was shown for the example quadruplet arraydescribed in reference to FIG. 7A. Instead of being mirror images of oneanother, the first and second antenna duplets 802, 804 may have the samestructure or may be rotated relative to one another. The particulararrangement of antenna duplets is chosen based, at least in part, on thecharging environment, and each particular arrangement creates differentradiation patterns and corresponding metrics/values (e.g., gain,back-to-front ratio, mutual coupling, etc.).

Antennas in the first antenna duplet 802 are spaced-apart by a distance(D) and antennas in the second antenna duplet 804 are spaced-apart by adistance (D). In some embodiments, the two distances (D) are the samewhile in other embodiments the two distances (D) are different. In someembodiments, the distance (D) is considerably less than 1λ (which isdetermined based on a center operating frequency of each of the antennaduplets 702, 704), e.g., D may be between ½λ to 1/30λ. Such closeinter-element spacing is not currently feasible for conventional antennastructures (especially for miniaturized antenna structures), as themutual coupling effects negatively impact radiation efficiency, rendingthese conventional duplets useful in densely packed antenna arrays.

Additional examples of the inter-element spacing distance (D) areprovided above with reference to FIG. 3A. The first and second antennaduplets 802, 804 are also spaced-apart by a separation distance (S). Theseparation distance (S) may be an example of the distance (D¹) and/orthe distance (D²) (FIG. 1). In some embodiments, the separation distance(S) is greater that the inter-element spacing distances (D), while inother embodiments the separation distance (S) is equal to or less thanthe inter-element spacing distances (D).

FIG. 8B illustrates a resulting radiation pattern 810 produced by thequadruplet array of FIG. 8A, in accordance with some embodiments. Theresulting radiation pattern 810 is produced when the first and secondantenna duplets 802, 804 are radiating together. The resulting radiationpattern 810 has a peak gain of 5.32 dB, as depicted in FIG. 8B.

FIG. 8C illustrates a cross-sectional view 820 of the resultingradiation pattern 810 (taken along the X-Y plane shown in FIG. 8B), inaccordance with some embodiments. The cross-sectional view 820 includesthe gain on the X-Z plane (Phi=0), as that plane is swept with aposition vector R of constant length |R|, originating at the axis'origin and rotating throughout that plane. During that operation, thetip of that vector indicates corresponding observation points on acircle of radius |R|, lying on the X-Z plane. The corresponding gaindiagrams are the gains observed at the (swept) observation pointsgenerated from the component of the electric field along the Y-axis(GainPhi, Phi=0) (i.e., the red curve is shrunk to a point) andgenerated by the component of the electric field perpendicular to theposition vector R as that vector sweeps the plane (GainTheta, Phi=0)(e.g., the blue curve). The cross-sectional view 820 also includes thegain on the Y-Z plane) (Phi=90°), as that plane is swept with a positionvector R of constant length |R|, originating at the axis' origin androtating throughout that plane. During that operation, the tip of thatvector indicates corresponding observation points on a circle of radius|R|, lying on the Y-Z plane. The corresponding gain diagrams are thegains observed at the (swept) observation points generated from thecomponent of the electric field along the X-axis (GainPhi, Phi=90°)(e.g., the green curve) and generated by the component of the electricfield perpendicular to the position vector R as that vector sweeps theplane (GainTheta, Phi=90°) (e.g., the purple curve is almost shrunk to apoint). From the fourth gain curves shown in the cross-sectional view820, (GainPhi, Phi=0) and (GainTheta, Phi=90°) are both negligible (veryclose to zero). The other two curves, (GainTheta, Phi=0) and (GainPhi,Phi=90°), show which electric field components the gain comes from, orwhat the polarization is of the radiation. On the Z-axis, thepolarization is along the X-direction, as both curves indicate. Further,these gains show a large front-to-back ratio (e.g., a majority of theradiated energy in the resulting radiation pattern 810 travelled awayfrom the antenna array 800 along the +Z-Axis, whereas a negligibleamount travelled in the opposite direction). This description can bereferenced and applied to the other cross-sectional views includedherein, and for the sake of brevity, duplicative description will not berepeated when describing those other cross-sectional views includedherein.

FIGS. 9A-1 to 9A-3 illustrate example octuplet antenna arrays, inaccordance with some embodiments. It is noted that the antennasillustrated in FIGS. 9A-1 to 9A-3 can be various sizes relative to oneanother, and the sizes shown in FIGS. 9A-1 to 9A-3 are examples only,and are not limiting. Moreover, the octuplet antenna arrays may includefour antenna duplets 600, some other antenna duplets, or variouscombinations of antenna duplets.

The octuplet arrays shown in FIGS. 9A-1 to 9A-3 have an overall length(L). In some embodiments, the overall length (L) is approximately 2λ(determined relative to a center operating frequency of each respectiveoctuplet array, e.g., a length of 750 mm for an example octuplet arraywith a center operating frequency of about 900 MHz), while in some otherembodiments the overall length (L) is substantially less (e.g., 1.5λ,1λ, or even less, such as 300 mm to 500 mm for an octuplet array with acenter operating frequency of about 900 MHz).

The octuplet arrays shown in FIGS. 9A-1 to 9A-3 also have acenter-to-center separation difference (Diff) between each antennaduplet. In some embodiments, the Diff. between each antenna duplet isthe same, while in other embodiments at last one Diff. is not the same.For example, a Diff. between the first and second duplets in theoctuplet of FIG. 9A-1 can be approximately 1λ (e.g., approximately 330mm for the example octuplet with the center operating frequency of about900 MHz), while a Diff. between the second and third duplets in theoctuplet of FIG. 9A-1 can be approximately ⅔λ (e.g., approximately 220mm for the example octuplet with the center operating frequency of about900 MHz).

In some embodiments, the center-to-center separation difference (Diff)is less than 1λ or even less than ¾λ (e.g., a Diff. of approximately 200mm between each respective duplet in the example octuplet with thecenter operating frequency of about 900 MHz), while in some otherembodiments the center-to-center separation difference (Diff) issubstantially less (e.g., less than ½λ or even smaller, such as 10 mm to100 mm for the example octuplet that has the center operating frequencyof 900 MHz, or some other range) or greater.

Conventionally, as the center-to-center difference (Diff) decreases,mutual coupling between adjacent antenna duplets (and more particularly,the antenna elements therein) increases to the point where the antennaelements become essentially inoperable as little to no radiation isbeing transmitted away from the duplets (instead this is being absorbedby neighboring antenna elements). By implementing the principlesdescribed herein and discovered by the inventors, mutual couplingbetween adjacent antenna elements in octuplet arrays (such as thoseshown in FIGS. 9A-1-9A-3, or any other arrays) remains at very lowlevels and, therefore, very densely packed antenna arrays can beconstructed.

Each of the example octuplet arrays of FIGS. 9A-1 to 9A-3 illustratedifferent ways to position respective duplets within the respectiveoctuplets. Various positioning arrangements are possible, includingserial distributed doublet array (FIG. 9A-1), parity-symmetricdistributed doublet array (FIG. 9A-2), rotation-symmetric distributeddoublet array (FIG. 9A-3). In some embodiments, the octuplet arrays ofFIGS. 9A-1 to 9A-3 are “uniformly distributed” (i.e., each of the Diff.values is substantially equal to one another such that thecenter-to-center distance between the respective duplets aresubstantially the same). Alternatively, the octuplet arrays of FIGS.9A-1 to 9A-3 can be “non-uniformly distributed” (i.e., at least oneDiff. value is not equal to the other Diff. values such that thecenter-to-center distance between the respective duplets differs in somerespect). In some embodiments, each of the example octuplet arrays 900,910, 920 are placed on a substrate (e.g., reflector 620, FIG. 6A).

Turning to FIG. 9B, a resulting radiation pattern is illustrated andrepresents the radiation pattern produced when the plurality of antennaduplets of the octuplet array 900 (FIG. 9A-1) collectively radiateelectromagnetic energy (i.e., the resulting radiation pattern 930 is acombination of radiation patterns generated by each of the plurality ofantenna duplets). As shown, the resulting radiation pattern 930 has apeak gain of 9.13 dB.

FIG. 9C illustrates a cross-sectional view 940 of the resultingradiation pattern 930 (taken along the X-Y plane shown in FIG. 9B). Across-sectional view, similar to cross-sectional view 940, is describedin further detail above with reference to FIG. 8C, and for the sake ofbrevity, said description is not repeated here.

FIG. 9D illustrates another resulting radiation pattern 950 that formswhen the plurality of antenna duplets of the antenna array 900 (FIG.9A-1) radiate electromagnetic energy, and FIG. 9E illustrates across-sectional view 960 of the resulting radiation pattern 950 (takenalong the X-Y plane shown in FIG. 9D). The results shown in FIGS. 9D and9E are obtained by applying an electronic phase shift of 180° to any oneof the two antennas (but not in both) in each respective duplet. Indoing so, the radiation pattern 950 is an approximate mirror image ofthe radiation pattern 930. The cross-sectional view 960 includes gainalong the X-axis (Phi) and gain along the Z-axis (Theta).

As such the antenna arrays described herein offer an additionaladvantage in that the transmitter 102 (FIG. 1) can now control whetherthe high-gain region is forward (low-gain region backward) or backward(low-gain region forward). This is electronic beam complete reversal,and is an additional unique feature exhibited by the pairing together ofco-polarized antennas that produce perpendicularly oriented radiationpatterns.

FIG. 9A-2 illustrates an octuplet array 910 placed on a substrate (e.g.,reflector 620, FIG. 6A) with a first set of antenna duplets that mirror,relative to dotted line, a second set of antenna duplets (also referredto as a parity-symmetric doublet array 910). The array 910 includes twoinstances of the quadruplet antenna array 800 (FIG. 8A), wherein the twoinstances are collinearly aligned along the Y-axis. FIG. 9A-3illustrates an octuplet array 920 placed on a substrate (e.g., reflector620, FIG. 6A) with a first set of antenna duplets rotated 180 degreesrelative to a second set of antenna duplets (e.g., rotated about thedotted line) (referred to as a rotation-symmetric doublet array).

Section C: Drop-In Antenna Structures

As described above, various improved antenna array designs are achievedby implementing the use of co-polarized antennas that produceperpendicularly oriented radiation patterns. The antenna structures thatexhibit these needed characteristics are now going to be described indetail. In particular, five different embodiments of antenna structuresthat exhibit these characteristics are described below. As will beappreciated by one of skill in the art, the antenna arrays describedabove (and elsewhere herein) may be designed by selecting any two ofthese antenna structures (e.g., one of the first embodiment drop-inantennas and one of the second embodiment drop-in antennas) and buildingan array of duplets (or other configurations) of these two antennastructures. Additionally, as will also be appreciated by one of skill inthe art, antenna arrays may also be built that include different duplets(e.g., a first duplet with the first and second embodiment drop-inantennas, a second duplet with the dual-polarized antennas, a thirdduplet with the two first embodiment antennas with decouplingmechanisms, and a fourth duplet that has the first embodiment drop-inantenna and the third embodiment drop-in antenna) and may be designedwith any number of these duplets to suit desired system characteristics.

The term “drop-in antenna” refers to an antenna structure that isdesigned so that its radiation characteristics (polarization andorientation of radiation pattern) remain unaffected by presence of alarge metal structure (e.g., a long rectangular metal reflector) thathas a long axis that is much larger than any dimension of the antennastructure. Typically, when an antenna is positioned on such a reflector,the antenna aligns its polarization with the long axis of the reflector.Accordingly, the drop-in antennas described below do not act in theconventional manner. For example, an example antenna structure that maybe termed a drop-in antenna structure may have a given polarization anda given orientation of radiation pattern, and this example antennastructure exhibits these same given radiation characteristics when thatstructure is place on top of a large metal structure.

Section C.1: First Embodiment of a Drop-In Antenna

FIGS. 10A-10C illustrate various views showing a first embodiment of adrop-in antenna 1000. The first embodiment drop-in antenna 1000 may bereferred to as a “stamped antenna” because antenna elements of theantenna 1000 are made from stamped metal. As shown in FIG. 10A, theantenna 1000 includes a substrate 1002 (e.g., a printed circuit board),a first radiating antenna element 1004, a second radiating antennaelement 1006, a third radiating antenna element 1008, tabs 1010-A,1010-B (also referred to herein as “folds” and “tuning stubs”), firstand second pins 1012, 1014 (also referred to herein as “feeds” in someembodiments), and a capacitor 1016. Radiating antenna elements may alsobe referred to herein simply as “radiating elements” or “radiators.”

The substrate 1002 has at least first and second orthogonal sides (e.g.,edges) that are both less than approximately 0.2λ in length. Forexample, with reference to FIG. 10B, a height (H) and width (W) of thesubstrate 10002 may be less than approximately 0.15λ in length. Toprovide some context, the antenna 1000 may be configured to operate atfrequencies ranging from one or more of 400 MHz (λ=0.75 meters) to 60GHz (λ=0.005 meters), depending on the application. Accordingly, whenthe antenna 1000 is operating at a frequency of approximately 900 MHz,the height (H) and width (W) are 50 millimeters or less. Moreover,depending on a shape of the substrate 1002, the height (H) and width (W)may be the same size or different sizes.

The first and second pins 1012, 1014 are substantially perpendicular toa top surface of the substrate 1002. Further, the first and second pins1012, 1014 are connected to and support the first and second antennaelements 1004, 1006, respectively (e.g., the substrate includes a firsthalf and a second half, and the first pin 1012 is positioned in thefirst half and the second pin 1014 is positioned in the second half ofthe substrate). In some embodiments, the first pin 1012 is configured toprovide electromagnetic signals to the first antenna element 1004 andthe second pin 1014 is configured to serve as a ground for the antenna1000. For example, the substrate 1002 may include a metal portion (i.e.,a grounding portion) connected to the second pin 1014. The metal portionmay serve to ground the antenna 1000 through its connection with thesecond pin 1014, and the substrate 1002 may also include an opening 1024(shown in magnified view 1020), where the opening 1024 is sized toreceive and accommodate the first pin 1012 (i.e., the opening isolatesthe first pin 1012 from the metal portion of the substrate 1002). Insuch embodiments, the first pin 1012 is connected to transmissioncircuitry 1022 (shown in magnified view 1020) that generates theelectromagnetic signals. When the first and second pins 1012, 1014 arearranged in this manner, the antenna 1000 may be configured to operateas a folded monopole antenna. The transmission circuitry 1022 is coupledto one or more of the power amplifier(s) 216 and the power feedingcircuitry 218.

Alternatively, in some embodiments, the first pin 1012 is configured toprovide electromagnetic signals to the first antenna element 1004 andthe second pin 1014 is configured to provide electromagnetic signals tothe second antenna element 1006 (e.g., the first pin 1012 is coupled toa first signal pad (e.g., transmission circuitry 1022) of the substrate1002 and the second pin 1014 is coupled to a second signal pad (e.g.,transmission circuitry 1022) of the substrate 1002). In suchembodiments, a voltage differential is created between the first pin1012 and the second pin 1014. For example, the first pin 1012 may beconfigured to provide electromagnetic signals at a higher power levelrelative to the second pin 1014, or vice versa. When the first andsecond pins 1012, 1014 are arranged in this manner, the antenna 1000 maybe configured to operate as a folded loop antenna. In some embodiments,the first antenna element 1004 is positioned in the first half of thesubstrate 1002, and the second antenna element 1006 is positioned in thesecond half of the substrate 1002.

As noted above, the first and second antenna elements 1004, 1006 arecoupled to the first and second pins 1012, 1014, respectively. In theillustrated example, the antenna elements 1004, 1006 and the pins 1012,1014 are coupled end-to-end. However, the first and second antennaelements 1004, 1006 may be coupled to the pins 1012, 1014 at variouslocations along a length of the antenna elements 1004, 1006. Further, insome embodiments, the antenna elements 1004, 1006 are both offset fromthe substrate 1002 (e.g., offset distance (D1), FIG. 10C). In such anarrangement, the substrate 1002 defines a first plane (e.g., a firsthorizontal plane: the bottom surface) and the first and second antennaelements 1004, 1006 define a second plane (e.g., a second horizontalplane: an intermediate surface) that is offset from the first plane. Insuch embodiments, the first and second antenna elements 1004, 1006 areco-planar (e.g., the first and second antenna elements 1004, 1006 areoffset from the substrate 1002 by the same distance). However, in someembodiments, the first and second antenna elements 1004, 1006 are offsetfrom the substrate 1002 by different distances.

The first antenna element 1004 follows a first meandering pattern andthe second antenna element 1006 follows a second meandering pattern. Insome embodiments, the first and second meandering patterns are the samewhile in other embodiments they differ. In those embodiments where thepatterns are the same, the first and second antenna elements 1004, 1006are mirror images of each other (e.g., symmetrical elements). The firstand second antenna elements 1004, 1006 are sometimes referred tocollectively as the “lower antenna element.” Various meandering patternsmay be used and the illustrated patterns are merely one set of examples.

The third antenna element 1008 is offset from the substrate 1002 (e.g.,offset distance (D2), FIG. 10C). The third antenna element 1008 definesa third plane (e.g., a third horizontal plane: the top surface) that isoffset from the second plane defined by the first and second antennaelements 1004, 1006. The third antenna element 1008 follows a thirdmeandering pattern. In some embodiments, the third meandering pattern ofthe third antenna element 1008 mirrors a combination of the meanderingpatterns followed by the first and second antenna elements 1004, 1006.Alternatively, in some embodiments, the third meandering pattern isdifferent from the meandering patterns followed by the first and secondantenna elements 1004, 1006. The third antenna element is sometimesreferred to as the “upper antenna element.”

The first, second, and third antenna elements 1004, 1006, 1008 eachfollow a meandering pattern (as discussed above), which is usedprimarily to reduce an overall size of the antenna 1000. By using themeandering patterns, the antenna elements 1004, 1006, 1008 can bepositioned within a boundary (i.e., a perimeter) of the substrate 1002.For example, with reference to FIG. 10B, a largest dimension (L1) of theillustrated antenna element is less than the height (H) (and in someembodiments the width (W)) of the substrate 1002. It is noted thatmeandering, antenna element widths, and upper-lower antenna elementseparations can be adjusted to optimize performance at other frequenciesor when a substrate is used.

In some embodiments, each of the first, second, and third antennaelements 1004, 1006, 1008 includes a plurality of segments. In someembodiments, the plurality of segments are contiguous segments while inother embodiments the segments are continuous segments.

The tabs 1010-A, 1010-B connect the third antenna element 1008 with thefirst and second antenna elements 1004, 1006. In addition, the tabs1010-A, 1010-B may be configured to adjust an operating frequency of theantenna 1000. For example, with reference to FIG. 10B, increasing (ordecreasing) a magnitude of L4 adjusts the operating frequency of theantenna 1000. Accordingly, during manufacture of the antenna 1000, theantenna 1000 can be calibrated by attaching various tabs 1010-A, 1010-Bto the antenna 1000 and measuring the operating frequency of the antenna1000.

The capacitor 1016 is disposed on the substrate 1002 and coupled to oneor more the first and second pins 1012, 1014. The capacitor 1016 isconfigured to facilitate impedance matching for the antenna 1000. Indoing so, the capacitor 1016 ensures that the antenna 1000 radiateselectromagnetic signals in an efficient manner. In some embodiments, thecapacitor 1016 is an interdigital capacitor. In such embodiments, asshown in the magnified view 1020, the capacitor 1016 has an electrodepattern composed of two comb-like electrodes 1016-A and 1016-B.

In some embodiments, the antenna includes dielectric support materialdisposed periodically between (i) the first radiating element 1004 andthe third radiating element 1008, and (ii) the second radiating element1006 and the third radiating element 1008. Further, in some embodiments,the antenna includes additional dielectric support material disposedperiodically between the first and second radiating elements 1004, 1006and the substrate 1002. The various other antennas described herein mayinclude similar arrangements of dielectric support material.

FIG. 10B is a top view of the antenna 1000 in accordance with someembodiments. In this example, the third antenna 1008 mirrors acombination of the meandering patterns followed by the first and secondantenna elements 1004, 1006. As a result, the first and second antennaelements 1004, 1006 are not visible in the depicted top view of FIG.10B. However, as discussed above, the first and second antenna elements1004, 1006 may have meandering patterns that differ from the meanderingpattern of the third antenna element 1008. In such cases, the firstand/or second antenna elements 1004, 1006 would be visible in a topview.

As discussed above, a height (H) and width (W) of the substrate 10002may be less than approximately 0.2λ in length. In some embodiments, thedimensions for the height (H) and width (W) of the substrate 1002 mayrange from approximately 0.05λ to 0.2λ, although other ranges arepossible. Further, physical dimensions of the antenna element 1008include but are not limited to a length (L1) of the antenna element1008, a length (L2) of the antenna element 1008, and a length (L3) ofthe antenna element 1008. In some embodiments, a value for each of thephysical dimensions is defined according to a wavelength (λ) and acenter operating frequency of electromagnetic signals to be radiated bythe antenna element. For example, the antenna 1000 can be dimensioned tocause transmission of electromagnetic signals at frequencies rangingfrom one or more of 400 MHz (λ=0.75 meters) to 60 GHz (λ=0.005 meters),depending on the application. Accordingly, when the antenna 1000 isoperating at a center frequency of approximately 900 MHz, the length(L1) is approximately 44.8 mm, the length (L2) is approximately 4.5 mm,and the length (L3) is approximately 18.36 mm. One skilled in the artwill appreciate that the dimensions above are merely one example.Various other dimensions are possible, depending on the circumstances.

FIG. 10C is a side view of the antenna 1000 in accordance with someembodiments. In this example, the first and second antennas 1004, 1006are co-planar. As a result, the second antenna element 1006 is notvisible in the depicted side view. However, as discussed above, thefirst and second antenna elements 1004, 1006 may not be co-planar, atleast in some embodiments. In such cases, the first and second antennaelements 1004, 1006 would be visible in a side view. Using the examplefrom above, when the antenna 1000 is operating at the center frequencyof approximately 900 MHz, the offset distance (D1) is approximately 5.44mm and the offset distance (D2) is approximately 8.1 mm. One skilled inthe art will appreciate that the dimensions above are merely oneexample. Various other dimensions are possible, depending on thecircumstances.

FIG. 10D illustrates a radiation pattern 1030 generated by the antenna1000 in accordance with some embodiments. The antenna 1000 is configuredto generate a radiation pattern 1030 polarized in a first direction(e.g., along the Y-axis), e.g., in response to electromagnetic wavesbeing fed to the antenna 1000 through the transmission circuitry 1022(FIG. 10A). In this example, the radiation pattern 1030 has a higherconcentration of EM energy produced along the Z-axis and the X-axis (andhas a radiation null along the Y-axis) and forms an overall torus shapehaving a peak gain of approximately 1.41 decibels (dB).

FIG. 10E illustrates a cross-sectional view 1040 of the radiationpattern 1030 (taken along the X-Z plane shown in FIG. 10D). FIG. 10Fillustrates a cross-sectional view of the radiation pattern 1030 (takenalong the Y-Z plane shown in FIG. 10D). As shown in both cross-sectionalviews, the antenna 1000 creates a substantially uniform radiationpattern. Cross-sectional views of radiation patterns are discussed infurther detail above with reference to FIGS. 3D and 6D.

Section C.2: Second Embodiment of a Drop-In Antenna

FIGS. 11A-11B illustrate various views showing a second embodiment of adrop-in antenna 1100. The antenna 1100 may replace the second antenna612 (FIG. 6A). The antenna 1100 is a printed version of the antenna 1000(FIG. 10A), and, thus, for the sake of brevity, features common to theantennas 1000, 1100 are given an abbreviated description below, whenappropriate. Moreover, dimensions of the 1100 may be smaller (e.g., by ascaling fraction equal to the inverse index of refraction of thematerial on which the antenna is printed) to the dimensions discussedabove with reference to the antenna 1000, unless specified otherwise.

The antenna 1100 may be referred to as a printed antenna 1100 becauseantenna elements of the antenna 1100 may be printed, at least partially.As shown in FIG. 11A, the antenna 1100 includes a first substrate 1102(e.g., a printed circuit board), a second substrate 1103 (e.g., aprinted circuit board), a first antenna element 1104, a second antennaelement 1106, a third antenna element 1108, vias 1110-A, 1110-B, firstand second pins 1112, 1114, and a capacitor 1116. Further, in someembodiments, the antenna 1100 includes first tuning elements 1120, 1122and/or second tuning elements 1122, 1124.

The first substrate 1102 may be an example of the substrate 1002. Thesecond substrate 1103, which is offset from the first substrate 1102,includes first and second opposing surfaces. As shown in FIG. 11B, thesecond substrate 1103 is offset from the first substrate 1102 by adistance (D). In some embodiments, the first substrate 1102 and thesecond substrate 1103 are the same while in other embodiments theydiffer in some respect. It is noted that the second substrate 1103 issemi-transparent in FIG. 11A for ease of discussion and illustration(e.g., to show the capacitor 1116, which is attached to the firstsurface of the second substrate 1103).

The second substrate 1103 is configured to receive the first, second,and third antenna elements 1104, 1106, and 1108. In the illustratedembodiment, the first antenna element 1104 is deposited (e.g., printed)onto the first surface of the second substrate 1103 and the secondantenna element 1106 is also deposited onto the first surface of thesecond substrate 1103. Further, the third antenna element 1108 isdeposited onto the second surface of the second substrate 1103. In someembodiments, the first and second antenna elements 1104, 1106 aresimilar to the first and second antenna elements 1004, 1006, and thethird antenna element 1108 is similar to the third antenna element 1008.Accordingly, for the sake of brevity, any duplicative description of theantenna elements is not repeated here. It is noted that the antennaelements 1104, 1106, 1108 may be switched, such that the third antennaelement 1108 is deposited on the first surface and the first and secondantenna elements 1104, 1106 are deposited on the second surface of thesecond substrate 1103. Moreover, in some embodiments, the antennaelements 1104, 1006, 1108 are a continuous piece of material (e.g.,similar to the antenna elements illustrated in FIG. 10A). Alternatively,the antenna elements 1104, 1006, 1108 may be separate segments that arecontiguous (e.g., abutting end-to-end with one another).

In some embodiments, at least one antenna element in the antenna 1100differs from the antenna elements in the antenna 1000. For example, aashown in FIG. 11A, the third antenna element 1108 includes a pluralityof segments 1109-A, 1109-B, 1109-C, etc., where some of the segments inthe plurality (e.g., segments 1109-A, 1109-B) are separated from eachother by tuning elements (e.g., tuning elements 1122). Although notshown, the first and second antenna elements 1104, 1106 may be depositedin the same manner. Alternatively, only one of the antenna elementsincludes tuning elements (e.g., the third antenna element 1108), in someother embodiments. The tuning elements used in the antenna 1100 arediscussed below.

The first and second pins 1112, 1114 are substantially perpendicular tothe first substrate 1102 and the second substrate 1103. Further, thepins 1112, 1114 are configured to support the second substrate 1103,along with the components on the second substrate 1103. The first andsecond pins 1112, 1114 are analogous to the first and second pins 1012,1014 (FIG. 10A).

In the illustrated example, the capacitor 1116 is coupled to the firstsurface of the second substrate 1103. However, the capacitor 1116 may beattached to the second surface of the second substrate 1103, or may beattached to the first substrate 1102 (e.g., similar to the attachmentbetween the substrate 1002 and the capacitor 1016, FIG. 10A). Thecapacitor 1116 is analogous to the capacitor 1016 (FIG. 10A).

The vias 1110-A, 1110-B connect the third antenna element 1008 with thefirst and second antenna elements 1004, 1006. The vias 1110-A, 1110-Bpass through the second substrate 1103 and each end of each via 1110contacts one of the antenna elements 1104, 1106, 1108. In someembodiments, instead of using the vias 1110, metal pieces (e.g.,electrical traces) are coupled to (or deposited on) lateral surfaces ofthe second substrate 1103, and the metal pieces connect antenna elementsdeposited on opposing surfaces of the second substrate 1103.

As noted above, in some embodiments, the antenna 1100 includes tuningelements configured to adjust an operating frequency of the antenna1100. In the illustrated embodiment, the antenna 1100 includes one ormore first tuning elements 1120 positioned between first segments of thethird antenna element 1108 and one or more second tuning elements 1122positioned between second segments (e.g., segments 1109-A and 1109-B) ofthe third antenna element 1108. The first and second tuning elements1120, 1122 can be used to adjust the operating frequency of the antenna1100 by connecting a respective tuning element to the separated segmentsof the third antenna element 1108, thereby creating an electrical shortacross the respective tuning element, and modifying an overall length ofthe third antenna element 1108.

Further, in some embodiments, the antenna 1100 includes one or morethird tuning elements 1124 positioned along an edge of the secondsubstrate 1103 and one or more fourth tuning elements 1126 alsopositioned along the edge of the second substrate 1103. The third andfourth tuning elements 1124, 1126 can also be used to adjust theoperating frequency of the antenna 1100 by connecting one or more of thethird and fourth tuning elements to the third antenna element 1108. Inthe illustrated embodiment, the third and fourth tuning elements 1124,1126 each includes four distinct tuning elements; however, the third andfourth tuning elements 1124 may include greater (or lesser) numbers oftuning elements.

The magnified views 1123 and 1125 of FIG. 11A illustrate connectionsbetween tuning elements and the third antenna element 1108. For ease ofdiscussion below, connections 1127-A-1127-D and 1128-A-1128-L areelectrical switches. The switches may include one or more transistors ordiodes that selectively couple one or more of the tuning elements to thethird antenna element 1108. The connections could also be metaldeposits, such as solder. For example, the tuning elements may bemanufactured without a connection to an antenna element and one or moreof the tuning elements may be connected to (e.g., or disconnected from)by soldering a connection (e.g., or removing a soldered connection) toconnect (e.g., or disconnect) the tuning element to the antenna element.In some embodiments (e.g., when solder is used), one or more of theconnections 1127-A-1127-D and 1128-A-1128-L are not included in theantenna 1100.

With reference to magnified view 1123, an electrical switch 1127-A ispositioned between an end portion of the third antenna element 1108 anda first tuning element 1124-A. The remaining electrical switches 1127-B,1127-C, and 1127-D are positioned between the remaining tuning elements1124-B, 1124-C, and 1124-D. Each electrical switch 1127 is switchablycoupled to one or more of the tuning elements 1124-A-1124-D. In someembodiments, the switches 1127-A-1127-D are controlled by a controllerof the transmitter 102 (FIG. 1), and the controller may adjust anoperating frequency and/or bandwidth of the antenna 1100 by connectingone or more of the tuning elements 1124-A-1124-D through a correspondingswitch (or switches). For example, the antenna 1100 has a firstoperating frequency when the first tuning element 1124-A is connected tothe third antenna element 1108 through the first switch 1127-A, theantenna 1100 has a second operating frequency, different from the firstoperating frequency, when the first and second tuning elements 1124-A,1124-B are connected to the third antenna element 1108 through the firstand second switches 1127-A, 1127-B, respectively, and so on. Althoughnot shown, the fourth tuning elements 1126 may include the samearrangement shown in the magnified view 1123.

With reference to magnified view 1125, electrical switches 1128-G-1128-Lare disposed between segment 1109-D of the third antenna element 1108and tuning elements 1120-A-1120-F. Further, electrical switches1128-A-1128-F are disposed between segment 1109-E of the third antennaelement 1108 and the tuning elements 1120-A-1120-F. In some embodiments,each electrical switch 1128 is switchably coupled to one of the tuningelements 1120-A-1120-F. In some embodiments, the switches 1127-A-1127-Fand/or 1127-G-1127-L are controlled by a controller of the transmitter102 (FIG. 1), and the controller may adjust an operating frequency ofthe antenna 1100 by connecting one of the tuning elements 1124-A-1124-Ewith the segments 1009-D and 1109-E through corresponding switches. Forexample, the antenna 1100 has a first operating frequency when the firsttuning element 1120-A is connected with the two segments 1109-D, 1109-Eof the third antenna element 1108 through switch 1127-A and switch1128-G, the antenna 1100 has a second operating frequency, differentfrom the first operating frequency, when the second tuning element1120-B is connected with the two segments 1109-D, 1109-E of the thirdantenna element 1108 through switch 1127-B and switch 1128-H, and so on.Although not shown, the second tuning elements 1122 may include the samearrangement shown in the magnified view 1125.

It is noted that the electrical switches 1128-A-1128-F or the electricalswitches 1128-G-1128-L are optional. For example, the electricalswitches 1128-A-1128-F (or the switches 1128-G-1128-L) may be replacedwith solder. Alternatively, the tuning elements 1120-A-1120-F may beintegrally formed with a segment of the third antenna element 1108,thereby forming a comb-shaped segment (e.g., the segment 1109-D or thesegment 1109-E would have a comb shape). In doing so, the antenna 1100only includes a single set of switches (e.g., switches 1128-A-1128-F orswitches 1128-G-1128-L), which simplifies manufacture of the antenna1100. Further, when one segment is comb-shaped, then a single switch maybe used to adjust the operating frequency of the antenna 1100.

In light of the above, in some embodiments, the controller of thetransmitter 102 can adjust the operating frequency of the antenna 1100using one or more sets of tuning elements (e.g., one or more of thefirst, second, third, and fourth tuning elements). In this way, theantenna 1100's operating frequency and/or bandwidth can be finelyadjusted. In some embodiments, the level of adjustment is approximately+/−15 MHz (although greater and lesser ranges are possible).

FIGS. 11C-1 to 11C-3 illustrate various coupling diagrams for the secondembodiment of the drop-in antenna 1100 when it is operating at differentfrequencies. The various operating frequencies can be obtained, at leastin some embodiments, using the tuning elements discussed above. Forexample, with reference to FIG. 11C-1, the antenna 1100 is tuned tooperate at approximately 856 MHz. As such, the coupling effect is thelowest when the antenna 1100 is operating at approximately 856 MHz. Incontrast, the antenna 1100 is tuned to operate at approximately 886 MHzand 905 MHz in FIGS. 11C-2 and 11C-3, respectively. As such, thecoupling effect is the lowest when the antenna 1100 is operating atthose respective operating frequencies. The operating frequenciesillustrated in FIGS. 11C-1-11C-3 are merely used to provide context, andthe antenna 1100 is capable of operating at greater and lesserfrequencies than those shown in FIGS. 11C-1-11C-3.

Section C.3: Third Embodiment of a Drop-In Antenna

FIGS. 12A-12D illustrate various views of a third embodiment of adrop-in antenna 1200 in accordance with some embodiments. The antenna1200, when placed in an antenna duplet, is designed to generate aradiation pattern that is perpendicular to a radiating pattern generatedby the other antenna in the antenna duplet, while also beingco-polarized with the other antenna. For example, the antenna 1200 maybe an example of the first antenna 602 (FIG. 6A).

The antenna 1200 includes a substrate 1208 including first and secondopposing surfaces (e.g., the first opposing surface shown as anupward-facing surface of the top layer of the substrate). The firstopposing surface of the substrate 1208 is shown from a top perspectiveview in FIGS. 12B-12D. The first surface includes at least one lateraledge extending end-to-end across the substrate 1208, and that onelateral edge is less than approximately 0.15λ in length (in certaincases, all four lateral edges are less than approximately 0.15λ inlength.

In some embodiments, the substrate 1208 is composed of a dielectricmaterial. In some embodiments, the substrate 1208 includes a singlelayer (e.g., the top layer shown in FIG. 12A). In some embodiments, thesubstrate 1208 includes a plurality of layers 1218 (as labeled in FIG.12A).

The antenna 1200 further includes a radiating element 1202 coupled tothe first surface of the substrate 1208 and separated from the at leastone lateral edge by a non-zero distance. The radiating element 1202 maybe a metal patch (e.g., of a patch antenna). In some embodiments, theradiating element 1202 is a metallization layer that is coupled to(e.g., on top of) the substrate 1208. In some embodiments, the radiatingelement 1202 (e.g., patch) is smaller (e.g., shorter in length on one ormore of the edges and/or smaller by area) than the substrate 1208.

For example, as shown in FIGS. 12A-12D, there is a gap (e.g., a non-zerodistance) between the edges of substrate 1208 and the radiating element1202 (e.g., at least one edge of the radiating element does not extendto an edge of the substrate). In some embodiments, a length of an edgeof the radiating element 1202 is shorter than the length of the at leastone edge of the substrate 1208. The radiating element 1202 may beprinted onto the first surface of the substrate 1208 and the secondsurface of the substrate 1208 operates as a ground plane (e.g., theantenna 1200 may be manufactured on a printed circuit board (PCB)).

In some embodiments, the substrate 1208 is substantially square orrectangular in shape. In some embodiments, the radiating element 1202 issubstantially square or rectangular in shape (e.g., the shape mayinclude cutouts on the edges and/or within the shape). In someembodiments, the substrate 1208 and the radiating element 1202 share thesame shape (e.g., both have substantially square shapes).

In some embodiments, as shown in FIG. 12A, the substrate 1208 furtherincludes a plurality of layers 1218, where each layer of the pluralityof layers 1218 has at least one edge that is aligned with the at leastone lateral edge of the first surface of the substrate 1208. Forexample, as shown in FIG. 12A, the plurality of layers 1218 appearsstacked between the first surface of the substrate 1208 (e.g., the top,upward-facing surface) and the second surface of the substrate 1208(e.g., the bottom, downward-facing surface).

The radiating element 1202 defines a first cutout 1206 and a secondcutout 1204, distinct from the first cutout 1206. In some embodiments,the second cutout 1204 has a second shape distinct from the first shapeof the first cutout 1206. The second cutout 1204 can be a simplerectangle, a rectangular ellipsoid (e.g., a curved slot with a long axisfollowing the long axis of the second cutout 1204), and variousmeandering shapes. The rectangles of the second cutout 1204 can bereplaced with semi-circles.

Relative to a normal rectangular strip, the meandered shape of thesecond cutout 1204 (also referred to as a “meandering slot”) increasesthe effective slot length, thus resulting in a lower resonant frequencyof the antenna 1200 and reducing a size of the antenna 1200. It is notedthat an increase in a size of the first cutout 1206 reduces an impedancematching bandwidth of the radiating element 1202. Therefore, a balancebetween increasing the size of the first cutout 1206 and reducing anarea of the radiating element 1202 needs to be observed.

In some embodiments, the first cutout 1206 is a circular cutout (asshown in FIGS. 12A-12D) while in other embodiments the first cutout issome different shape (e.g., rectangular, triangular, etc.). Thediscussion above concerning the size of second cutout 1204 also appliesto the first cutout 1206. For example, an increase in a size of thesecond cutout 1204 reduces an impedance matching bandwidth of theradiating element 1202.

Plane 1219 in FIG. 12A is referred to as a “Virtual Symmetry Plane,”which is a plane of symmetry of the antenna 1200, given that the feedvia 1214 (discussed below) is close to the plane 1219. The antenna 1200effectively operates as if there are two antennas: the original one, andone that is reflected across the symmetry plane 1219, which is close toa top of the original one. The original antenna and its “image” obtainedfrom this symmetry plane 1219 (virtual mirror) operate as if there aretwo real antennas connected. The advantage of this virtual reflection isthat, in practice, the existing antenna is much smaller because it worksas if it coexists with its image. Therefore, the antenna 1200 operatesas if it were double its actual size. Hence, the structure of theantenna 1200 reduces a size of the antenna 1200 significantly.

The antenna 1200 further includes the feed 1214 (the radiating element1202 is shown as semi-transparent for ease of illustration anddiscussion), defined through the substrate 1208 (e.g., through theplurality of layers 1208), that couples the radiating element 1202 totransmission circuitry (e.g., power amplifier(s) 216 and power feedingcircuitry 218, FIG. 2A) of the transmitter 102. In some embodiments, asshown in FIG. 12D, the antenna 1200 further includes one or moreshorting vias 1216 that are defined through the substrate 1208 thatcouple the first surface with the plurality of layers 1218. In someembodiments, the one or more shorting vias 1216 are connected (e.g.,shorted) through the plurality of layers 1218 of the substrate 1208 tocreate a cavity-backed antenna (e.g., the shorting vias 1216 can be allconnected, and they also connect to the ground, which is the bottommetal layer of the antenna 1200). In some embodiments, the one or moreshorting vias 1216 are not present (e.g., or are present but notelectrically connected through the substrate) to create anon-cavity-backed antenna. It is noted that the cavity-backed (withshorting vias as shown) embodiments provide higher efficiency and lowerresonant frequency (effectively reducing antenna size) than thoseembodiments without the shorting vias 1216.

When the shorting vias 1216 are absent, the only via is the feed 1214,which is a metal pin connecting the antenna 1200 to a hole in theground. The electromagnetic signals will be applied in that hole,between the ground conductor and the feed 1214, which is the signalterminal of the antenna.

In some embodiments, the antenna 1200 further includes one or moretuning elements (e.g., tuning elements 1210 and 1212) switchably (ornon-switchably) connected to the radiating element 1202. Any subset(from none to all) of the one or more tuning elements may connected tothe radiating element 1202 at any given time. In some embodiments, theone or more tuning elements are connected to the radiating element 1202using an electrical switch, as represented in FIG. 12D as the dashedcircles, including switches 1220-1 and 1220-2. The switches may includeone or more transistors or diodes that couple the one or more tuningelements to the radiating element 1202.

For example, the one or more transistors may be set to “on” to connect(e.g., electrically couple) the one or more tuning elements to theradiating element 1202. Conversely, the one or more transistors may beset to “off,” such that the one or more tuning elements are notconnected to the radiating element 1202. In some embodiments, some(e.g., from none to all) of the transistors are set to “on” and some(e.g., from none to all) of the transistors are set to “off,” thus asubset of the one or more tuning elements may be connected to theradiating element 1202 at any given time. In some embodiments, the stateof the transistors (e.g., “on” or “off”) is controlled from anelectronic device (e.g., a controller of the transmitter 102) remotefrom the antenna 1200. In some embodiments, the one or more tuningelements are switchably connected to the radiating element 1202 bysoldering a connection between the one or more tuning elements and theradiating element 1202. For example, the one or more tuning elements maybe manufactured without a connection to the radiating element and theone or more tuning elements may be connected to (e.g., or disconnectedfrom) by soldering a connection (e.g., or removing a solderedconnection) to connect (e.g., or disconnect) the one or more tuningelements to the radiating element.

The one or more tuning elements are configured to adjust an operatingfrequency and/or bandwidth of the radiating element 1202. In someembodiments, the one or more tuning elements are configured to adjustthe operating frequency of the radiating element based on signals from acontroller managing operation of the antenna (e.g., controlling whetherto turn the transistors “on” or “off” by a controller). For example, ifthe controller turns a first transistor, coupled to a first tuningelement, “on,” the first tuning element is then connected to theradiating element 1202.

As shown in FIG. 12B, in some embodiments, the one or more tuningelements 1210-1, 1210-2 include a plurality of concentric ringspositioned within the first cutout 1206 (e.g., a circular cutout). Insome embodiments, the rings in the plurality of concentric rings do notoverlap, as shown by the circular cutout areas 1206 shown between theradiating element and each of the concentric rings 1210-1 and 1210-2. Insome embodiments, adjusting the frequency of the radiating elementincludes connecting a first concentric ring 1210-1 of the plurality ofconcentric rings to the radiating element 1202, and connecting the firstconcentric ring changes the operating frequency of the radiating elementfrom a first frequency to a second frequency greater than the firstfrequency (e.g., up tunes the operating frequency). In some embodiments,adjusting the operating frequency of the radiating element furtherincludes connecting two or more concentric rings of the plurality ofconcentric rings to the radiating element, where the two or moreconcentric rings include the first concentric ring. For example, thefirst concentric ring 1210-1 and second concentric ring 1210-2 may beconnected using switch 1220-2. Connecting the two or more concentricrings changes the operating frequency of the radiating element from thesecond frequency to a third frequency greater than the second frequency(e.g., and greater than the first frequency from connecting the firstconcentric ring). In some embodiments, the first concentric ring 1210 isconnected with the radiating element 1202 (e.g., along the edge of thecutout of the radiating element) by a switch.

In some embodiments, the first cutout 1206 (e.g., the circular cutout)has a first radius and the plurality of concentric rings include a firstconcentric ring that is switchably connected to the radiating elementand has a second radius, smaller than the first radius. For example, thefirst concentric ring (e.g., concentric ring 1210-1) is smaller than thefirst cutout 1206. In some embodiments, the plurality of concentricrings further includes a second concentric ring (e.g., concentric ring1210-2) that is switchably connected to the first concentric ring andhas a third radius, smaller than the second radius. Accordingly, thesecond concentric ring is switchably connected to the radiating element1202 through the first concentric ring (e.g., the first and secondconcentric ring may be serially connected to the radiating element). Insome embodiments, the plurality of concentric rings includes more thantwo concentric rings, each subsequent ring having a smaller radius andswitchably connected to its neighboring ring (e.g., the ringsimmediately next to the respective ring). In some embodiments, theplurality of concentric rings includes four concentric rings. In someembodiments, a number of possible tuning states to which the operatingfrequency of the antenna 1200 can be adjusted includes the number ofconcentric rings plus one. For example, if there are M (where M is aninteger) concentric rings, the antenna has M+1 distinct tuning states.

In some embodiments (as an alternative or in addition to the serialconnection described above), each ring is connected individually to theradiating element 1202. For example, a third ring may be connected tothe radiating element 1202 without connecting the first and/or secondconcentric rings (that are positioned between the third ring and theradiating element 1202).

As shown in FIG. 12C, in some embodiments, the one or more tuningelements include a plurality of rectangular segments 1212 on the firstsurface of the substrate 1208. In some embodiments, at least one of theplurality of rectangular segments is positioned along the at least oneedge of the first surface of the substrate, as shown in FIGS. 12C and12D. In some embodiments, adjusting the operating frequency of theradiating element 1202 includes connecting a first rectangular segmentof the plurality of rectangular segments, where connecting the firstrectangular segment changes the operating frequency of the radiatingelement 1202 from a first frequency to a second frequency less than thefirst frequency (e.g., down tunes the operating frequency). In someembodiments, adjusting the operating frequency of the radiating element1202 further includes connecting two or more rectangular segments of theplurality of rectangular segments to the radiating element 1202, wherethe two or more rectangular segments include the first rectangularsegment.

For example, the first rectangular segment and a second rectangularsegment are both connected. In some embodiments, a number of possibletuning states to which the operating frequency of the antenna can beadjusted includes 2 raised to the power of the number of rectangularsegments of the antenna. For example, if there are N (where N is aninteger) rectangles, the antenna has 2^(N) distinct tuning states.

In some embodiments, as shown in FIG. 12D, the one or more tuningelements include a combination of a plurality of concentric ringspositioned within the first cutout and a plurality of rectangularsegments on the first surface of the substrate. In some embodiments,adjusting the operating frequency of the radiating element 1202 includesconnecting at least one of the plurality of concentric rings to theradiating element 1202 (e.g., to up-tune the operating frequency) andconnecting at least one of the plurality of rectangular segments to theradiating element 1202 (e.g., to down-tune the operating frequency). Insome embodiments, the tuning range for the operating frequency includeschanging the starting operating frequency (e.g., without the tuningelements connected) by approximately 20% (e.g., by 10% in eitherdirection, up-tuning or down-tuning). This allows for greaterflexibility in tuning the operating frequency of the antenna 1200. Insome embodiments, the amount that the operating frequency is adjusted isdependent upon how many of the concentric rings and/or how many of therectangular segments are connected to the radiating element. Thus, byselectively connecting a combination of concentric rings and/orrectangular segments, the operating frequency may be tuned to a desiredfrequency.

FIGS. 12E-1 and 12E-2 illustrate various configurations of the tuningelements 1212 in accordance with some embodiments. In this particularexample, there are five tuning elements 1212, and the tuning elements1212 that are connected to the radiating element 1202 in each shownconfiguration are colored black. Accordingly, from Newton's binomialtheorem, there are 32 different combinations of the tuning elements 1212(i.e., FIGS. 12E-1 and 12E-2 illustrate 32 different configurations).The number of tuning elements 1212 may of course change, depending onthe circumstances, and therefore additional configurations are possible(i.e., 2^(N) distinct tuning states where N is the number of tuningelements, as discussed above). Further, assuming the antenna 1200includes five of the tuning element 1210 (i.e., ring tuning elements),then a total of 160 different tuning configurations can be obtained.Thus, the antenna's 1200 operating frequency can be finely adjustedusing the tuning elements 1212 (and the tuning elements 1210). In someembodiments, the level of adjustment is approximately +/−20% (althoughgreater and lesser ranges are possible). It is noted that physicalconnections between the radiating element 1202 and the tuning elements1212, e.g., as shown in FIG. 12F, are not shown in FIGS. 12E-1 and 12E-2for ease of illustration. In practice, the tuning elements shown inFIGS. 12E-1 and 12E-2 are physically connected to the radiating element1202.

FIGS. 12F-12H illustrate various coupling diagrams for the antenna 1200when the antenna 1200 is operating at different frequencies. The variousoperating frequencies can be obtained, at least in some embodiments,using the tuning elements 1210, 1212 discussed above. For example, withreference to FIG. 12F, the antenna 1200 is tuned to operate atapproximately 880 MHz (e.g., each of the tuning elements 1212 is coupledwith the radiating element 1202). As such, the coupling effect is thelowest when the antenna 1200 is operating at approximately 880 MHz. Incontrast, the antenna 1200 is tuned to operate at approximately 940 MHzand 950 MHz in FIGS. 12G and 12H, respectively. As such, the couplingeffect is the lowest when the antenna 1200 is operating at thoserespective operating frequencies. The difference between FIGS. 12G and12H is that the antenna 1200 in FIG. 12G includes two interconnectedtuning elements 1210, whereas the antenna 1200 in FIG. 12H includes fourinterconnected tuning elements 1210. The operating frequenciesillustrated in FIGS. 12F-12H, and the tuning element configurations, aremerely used to provide context, and the antenna 1200 is capable ofoperating at greater and lesser frequencies than those shown in FIGS.12F-12H.

Section C.4: Fourth Embodiment of a Drop-In Antenna

FIGS. 14A-1 and 14A-2 illustrate embodiments a fourth embodiment of adrop-in antenna 1400 in accordance with some embodiments. In someinstances, the antenna 1400 may replace the first antenna 602 in theantenna duplet 600 (FIG. 6A). In such a configuration, the antenna 1400is configured to generate a radiation pattern that is perpendicular to aradiating pattern generated by the other antenna in the antenna duplet600. Configurations with various other antennas are also possible.

As shown in FIG. 14A-1, the antenna 1400 includes a first substrate 1402having first and second opposing surfaces, and a second substrate 1404having first and second opposing surfaces. The first and secondsubstrates 1402, 1404 may be made from dielectric materials. In someembodiments, one or more of the first and second substrates 1402, 1404is a printed circuit boards (PCB). In some embodiments, a largestcross-sectional dimension of the first and second substrates 1402, 1404is less than approximately 0.25λ in length. For example, if the antenna1400 is operating at 915 MHz, then a largest cross-sectional dimensionof the first and second substrates 1402, 1404 is less than approximately80 mm in length. Further, the first and second substrates 1402, 1404 maybe the same and different sizes. In some embodiments, the first surface(e.g., the surface connected to a reflector) of the first substrate 1402has a ground. The first substrate 1402 and the second substrate 1404 mayhave different characteristics. For example, the first substrate 1402may have a lower permittivity relative to a permittivity of the secondsubstrate 1404, or vice versa.

In some embodiments, the antenna 1400 includes sidewalls 1406 (e.g.,four sides) extending from the first substrate 1402 to the secondsubstrate 1404. Alternatively or in addition, the antenna 1400 includesa via fence 1412 (FIG. 14B) extending from the first substrate 1402 tothe second substrate 1404. For instance, the via fence 1412 could beplaced within the substrates 1402 and 1404, and when in the gap betweenthe substrates, the via fence 1412 is implemented as a conductive wall.In some embodiments, the sidewalls 1406 and/or the via fence 1412 wrapsaround a perimeter of the antenna 1400 (as shown in FIG. 14A-1).Alternatively, in some embodiments, the sidewalls 1406 and/or the viafence 1412 partially wraps around a perimeter of the antenna 1400 (asshown in FIG. 14A-2). For example, sidewalls 1406-A and 1406-B areseparated by openings 1407-A and 1407-B (FIG. 14A-2). The space betweenthe first and second substrates 1402, 1404 forms a cavity, which may befilled with air or a dielectric. The sidewalls 1406 may be made from aconductive metal, such as copper, and may be mechanically and/orchemically (e.g., using an adhesive) attached to the first and secondsubstrates 1402, 1404.

In some embodiments, using sidewalls 1406 and/or a via fence 1412 thatpartially wraps around the perimeter of the antenna 1400 changes aperformance of the antenna 1400. For example, a gain and radiationefficiency of the antenna 1400 can be improved by using sidewalls 1406and/or a via fence 1412 that partially wraps around the perimeter of theantenna 1400, relative to using sidewalls 1406 and/or a via fence 1412that completely wraps around the perimeter of the antenna 1400.

The antenna 1400 also includes a radiating element 1408 (e.g., a patchantenna) coupled to the second surface of the second substrate 1404. Oneor more edges of the radiating element 1408 follow a meandering pattern.In the illustrated example, two edges of the radiating element 1408follow symmetrical meandering patterns. The meandering serves thepurpose of reducing the total antenna size. The radiating element 1408is configured to generate a radiation pattern 1430 polarized in a firstdirection (e.g., aligned with the X-axis, FIG. 14D). In this illustratedexample of FIG. 14D, the radiation pattern 1430 has a higherconcentration of EM energy produced along the Z-axis and the X-axis (andhas a radiation null along the Y-axis), and forms an overall torus shapehaving a peak gain of 1.7 dB (FIG. 14D). As discussed above, radiationpattern 1430 may be changed if, say, the antenna 1400 is rotated 90degrees.

Further, the antenna 1400 can obtain a radiation efficiency ofapproximately 71%, depending on its configuration (e.g., its sidewallconfiguration).

In some embodiments, the radiating element 1408 includes one or moreslots (e.g., slots 1410-1 and 1410-2). The antenna 1400 can be tuned infrequency by changing the length of the slots 1410-1 and 1410-2 on theradiating element 1408. For example, increasing a length (or an area) ofone or more of the slots 1410-1 and 1410-2 can decrease an operatingfrequency of the antenna 1400, while decreasing a length (or an area) ofone or more of the slots 1410-1 and 1410-2 can increase an operatingfrequency of the antenna 1400.

FIG. 14B illustrates a top view of the antenna 1400, in accordance withsome embodiments. In this particular example, the antenna 1400 includesa via fence 1412 that wraps around the perimeter of the antenna 1400. Asdiscussed above, the via fence 1412 may wrap completely or partiallyaround the perimeter of the antenna 1400. It is also noted that theslots 1410-1, 1410-2 are shortened relative to the slots 1410-1, 1410-2shown in FIGS. 14A-1 and 14A-2.

FIG. 14C illustrates a cross-sectional view of the antenna 1400 (takenalong line A-A¹, FIG. 14B), in accordance with some embodiments. Asshown, the antenna 1400 includes a capacitor 1414 connected to theradiating element 1408 through a capacitor post 1416. The capacitor 1414is configured to achieve overall size reduction of the antenna andfacilitate impedance matching for the antenna 1400, and a size of thecapacitor 1414 can be tailored during manufacturer to achieve saidmatching. The antenna 1400 also includes a coaxial feed 1418 connectedto the radiating element 1408. The coaxial feed 1418 is configured toprovide electromagnetic signals to the radiating element 1408. Forexample, the coaxial feed is configured to receive electromagneticsignals from one or more power amplifiers of the power amplifier(s) 216.

FIG. 14D shows a radiation pattern produced by the antenna 1400, inaccordance with some embodiments. As explained above, the radiatingelement 1408 is configured to generate the radiation pattern 1430polarized in a first direction (e.g., aligned with the X-axis, FIG.14D). As also shown in FIG. 14D, the radiation pattern 1430 has asomewhat omnidirectional pattern in the XZ-plane, with maximum gain inthe positive Z-direction (with a radiation null forming along theY-axis) and forms an overall torus shape having a peak gain of 1.7 dB.

FIG. 14E illustrates a cross-sectional view 1440 of the resultingradiation pattern 1430 (taken along the X-Z plane shown in FIG. 14D), inaccordance with some embodiments. The dimensions of the antenna 1400 caneffect an operating frequency, radiation efficiency of the antenna 1400,and the resulting radiation pattern 1430, among other things. As oneexample, the antenna 1400, when operating at approximately 915 MHz andincluding a via fence 1412 that partially wraps around the perimeter ofthe antenna 1400 (e.g., as shown in FIG. 14A-2), achieved a radiationefficiency of approximately 71%. To obtain this operating frequency andradiation efficiency, the antenna 1400 had the following dimensions:D1=50.4 mm, D2=50.4 mm, D3=5.1 mm, D4=4.5 mm, D5=5.3 mm, D6=9.4 mm,D7=44.8 mm, D8=43 mm, D9=21.3 mm, D10=23.6 mm, D11=9.8 mm, and D12=28mm. Further, each of the slots 1410-1 and 1410-2 were 2×8 mm and thecapacitor 1414 was 7.2×7.2 mm. As shown in the cross-sectional view1440, the antenna 1400 creates a substantially uniform radiationpattern.

FIG. 14F is a diagram 1450 that shows impedance matching or thereflection coefficient at a feed for the antenna 1400, in accordancewith some embodiments. The curve S₁₁ shows measurements of the magnitudeof the reflection coefficient at the antenna 1400's feed port. As shown,the measurements of the reflection coefficient are very low.Accordingly, the antenna 1400 operates efficiency at its operatingfrequency of approximately 915 MHz (i.e., the antenna 1400 radiateselectromagnetic waves outwards when operating at 915 MHz).

Section D: Dual-Polarized Antenna

FIG. 13A illustrates a dual-polarized antenna 1300, in accordance withsome embodiments.

The antenna 1300 includes a substrate 1302 (e.g., a printed circuitboard) having first and second opposing surfaces. In some embodiments, alargest cross-sectional dimension of the substrate 1302 is less than0.25λ in length. The substrate 1302 may be made from a material havinglow permittivity, with suitable example materials with such lowpermittivity properties including the Rogers 4003 or the Isola 408HRmaterials.

The antenna 1300 includes a radiating element 1304 (e.g., a patchantenna) coupled to a surface of the substrate 1302. The radiatingelement 1304 is configured to generate a radiation pattern 1320(depicted in FIG. 13B-1) polarized in a first direction or a seconddirection (e.g., horizontally, such as along the x-axis, or vertically,such as along the y-axis).

The direction of polarization is based on which port provideselectromagnetic signals to the radiating element 1304. For example, ifport 1306-1 provides the electromagnetic signals, then the antenna 1300is horizontally polarized, whereas if port 1306-2 provides theelectromagnetic signals, then the antenna 1300 is vertically polarized.Further, when the antenna 1300 has dimensions of 100×100×5 mm, theradiation pattern 1320 achieved a peak gain of 4.89 dB (FIG. 13B) with aradiation efficiency of approximately 82%. It is noted that theradiating element 1304 is shown as semi-transparent for ease ofillustration and discussion.

The ports 1306-1, 1306-2 are attached to the substrate 1302 and areconfigured to receive electromagnetic signals from one or more poweramplifiers of the power amplifier(s) 216 (FIG. 2A). The ports 1306-1,1306-2 may be connected to the same power amplifier or different poweramplifiers.

FIG. 13B-2 is a diagram 1325 that shows mutual coupling effects for thedual-polarized antenna, in accordance with some embodiments. Curve S₂₁in the diagram 1325 illustrates that mutual coupling (i.e., couplingeffect) between the ports 1306-1, 1306-2 peaks at −25 dB when theantenna 1300 is radiating electromagnetic waves at 915 MHz (measuredbetween ports 1306-1, 1306-2 of the antenna 1300). The other curves S₁₁and S₂₂ show measurements of coupling effects between port 1306-1 withitself and 1306-2 with itself, respectively.

FIGS. 13D and FIG. 13E illustrate respective cross-sectional views 1340,1350 of the resulting radiation pattern 1320 (taken along the X-Z planeshown in FIG. 13B), in accordance with some embodiments. In particular,FIG. 13D is a cross-sectional view 1340 of the resulting radiationpattern 1320 when port 1306-1 is activated, and FIG. 13E is across-sectional view 1350 of the resulting radiation pattern 1320 whenport 1306-2 is activated.

FIG. 13E shows an example of an antenna array that includes a group ofthe dual-polarized antennas. As shown, the transmitter 102 (inembodiments where it includes the antenna array 1330) can selectivelyactivate port 1306-1 of each antenna 1300 in the array 1330 to achievean overall polarization in a first direction (e.g., verticalpolarization). Further, the transmitter 102 can selectively activateport 1306-2 of each antenna 1300 in the array 1330 to achieve an overallpolarization in a second direction (e.g., horizontal polarization).Selecting activating different ports in the antenna array 1330 isbeneficial when a polarization of the receiver's 120 antenna(s) isknown. For example, when the receiver's 120 antenna is horizontallypolarized, then the transmitter 102 can selectively activate thenecessary ports so that the electromagnetic waves radiated by theantenna array 1330 have a polarization that matches the polarization ofthe receiver's 120 antenna.

FIG. 13F illustrates mutual coupling effects (e.g., curves 1362 and1364) between antennas in the antenna array 1330, in accordance withsome embodiments. As discussed above, mutual coupling (i.e., the“coupling effect”) can be measured between respective ports/feeds ofantennas in an antenna array, and the coupling effect indicates anamount of radiated electromagnetic energy that is absorbed by, e.g., afirst antenna when a second antenna is radiating electromagnetic signals(and vice versa). For example, each antenna 1300 in the antenna array1330 has respective first and second ports 1306-1, 1306-2 (i.e., ports1-8 in total), and in this example, curve 1362 in the diagram 1360 wasproduced by activating/feeding each of the respective second ports1306-2 (the ports circled in FIG. 13E as “polarized in seconddirection,” which will be referred to simply as ports 1, 3, 5, and 7,respectively, moving from left-to-right across FIG. 13E). FIG. 13F showsthat the coupling effect between active ports 3 and 1 in the first andsecond instances of the antenna 1300, respectively, peaks atapproximately −14 dB when both antennas are radiating electromagneticwaves at approximately 915 MHz (curve 1364 shows a similar result formutual coupling effects between ports 3 and 5). The other curves 1366,1368, 1370, and 1372 show measurements of coupling effects between eachof ports 3, 3; 5, 5; 7, 7; and 1, 1, respectively.

FIG. 13G illustrates radiation patterns 1370 and 1380 generated by theantenna array 1330.

Section E.1: First Embodiment of a Multidimensional Dipole Antenna OverFolded Shield

FIGS. 15A-15E illustrate a first embodiment of a multidimensionalantenna over folded shield 1500. In certain embodiments, the antenna1500 is positioned near a decoupling mechanism (e.g., decoupling wall1522, FIG. 15C). In some embodiments, the antenna 1500 (or pairs of theantenna 1500) is (are) also included in antenna arrays that have theantenna duplets discussed above (e.g., these antennas 1500, or pairstherefore, may be positioned between the antenna duplets that haveco-polarized antennas). By creating antenna arrays that include both theduplets discussed above and the antennas 1500, certain antennas arraysmay be built that are capable of servicing differentwireless-power-receiving devices that may require differently polarizedpower waves.

FIG. 15A is a top view of the antenna 1500 in accordance with someembodiments. The antenna 1500 includes a substrate 1502 (e.g., a printedcircuit board or a ground plane) having a largest cross-sectionaldimension less than 0.25λ in length. For instance, the substrate 1502could be behind the ground plane, or the substrate 1502 could be leftout altogether if a balun is an external component. Additionalfeatures/components of the substrate 1502 are discussed below withreference to FIG. 15B.

The antenna 1500 includes a radiating element 1504 offset from a surfaceof the substrate (or the ground plane) 1502 (e.g., as shown in FIG.15C). The radiating element 1504 is configured to generate a radiationpattern polarized in a first direction. Further, when the antenna 1500has dimensions of D1=45 mm, D2=40 mm, and D3=26 mm, the antenna 1500achieved a peak gain of 3.4 dB with a radiation efficiency ofapproximately 83%. It is noted that the antenna 1500's design in FIGS.15A-15E is a stamped metal design, where the radiating element 1504 ison air. Similar performance can be achieved with a printed antennaversion on a substrate with low loss tangent (e.g., similar to thesubstrate 1103 configuration of the antenna 1100, FIG. 11A).

With reference to FIG. 15C, the radiating element 1504 includes an upperelement 1516 and two lower elements 1518-1 and 1518-2, which may beco-planar lower elements. The upper and lower elements follow meanderingpatterns, where the meandering patterns followed by the two lowerelements 1518-1 and 1518-2 can be symmetrical meandering patterns. Thefirst lower element 1518-1 connects with the upper element 1516 via twofolds 1517 (FIG. 15D), and the second lower element 1518-2 connects withthe upper element 1516 via two different folds 1517 (FIG. 15D). Thefolds 1517 (e.g., folds 1517-1 and 1517-2, FIG. 17C) may be part of theupper antenna element 1516, the lower antenna elements 1518-1, 1518-2,or some combination thereof. The meandering and folding serve thepurpose of reducing the total antenna size and increasing the radiationresistance of the structure. In some embodiments, dimensions of theradiating element 1504 (e.g., D3) range from approximately λ/7×λ/10,thereby making this a compact design. It is noted that meanderingshapes, antenna element widths, and upper-lower antenna elementseparations can be adjusted to optimize performance at other frequenciesor when a substrate is used. As shown in FIG. 15D, the two lowerelements 1518-1 and 1518-2 are distinct elements (i.e., split apart).Further, a symmetry of the radiation pattern and its broadside pointingdirection is ensured by having a symmetric structure “north and south”of the respective feed point.

Still with reference to FIG. 15C, first and second feeds 1514-1, 1514-2extend from the substrate 1502 and connect with the first and secondlower elements 1518-1, 1518-2, respectively (e.g., connection locations1519-1, 1519-2, FIG. 15D). The first and second feeds 1514-1, 1514-2 areconfigured to provide electromagnetic signals to the first and secondlower elements 1518-1, 1518-2, respectively. Further, theelectromagnetic signals provided to the first and second lower elements1518-1, 1518-2 travel to the upper element 1516 though the folds 1517,where the electromagnetic signals meander back towards a center of theupper element 1516.

With continued reference to FIG. 15C, the antenna 1500 is coupled to ametallic base 1520 (e.g., the substrate 1502 is mechanically and/orchemically attached to the base 1502). The metallic base 1520 improvesthe front-to-back ratio of the antenna 1500 by limiting backwardsradiation, thereby increasing forward gain. In some embodiments, anoptimized radiation efficiency can be achieved when the metallic base1520 has a length of approximately λ/2 (greater and lesser lengths canalso be used). The metallic base 1520 includes one or more sets ofdecoupling walls (e.g., decoupling wall set 1522-1, 1522-2) where eachset parallels two edges of the antenna 1500. The set of decoupling walls1522-1, 1522-2 extends away from the base 1520 to a height thatsubstantially matches a height of the antenna 1500. For example, aheight of the antenna 1500 may be approximately 10 mm while the heightof the decoupling walls may be approximately 11 mm. By placing theradiating element 1504 in close proximity to the decoupling wall set1522-1, 1522-2, three effects are achieved: (i) the resonance frequencyof the antenna 1500 is lowered, thus allowing for extra miniaturization,(ii) mutual coupling between two closely spaced instances of antenna1500 is considerably reduced (e.g., antennas 1500-1, 1500-2, FIG. 15E),and (iii) the radiation efficiency of the antenna array 1530 can beincreased.

With reference to FIG. 15B, the radiating element 1504 has been removedfor ease of illustration of aspects of the substrate 1502. The antenna1500 is designed in such a way that the electromagnetic signals providedto the first lower element 1518-1 by the first feed 1514-1 have a180-degree phase shift relative to the electromagnetic signals providedto the second lower element 1518-2 by the second feed 1514-2 (i.e., thefirst and second feeds 1514-1, 1514-2 are differential feeds). Toaccomplish this, the substrate 1502 includes lines 1507 and 1508 (alsoreferred to as “traces”) that split the electromagnetic signals, where(i) the line 1507 is connected to the first lower element 1518-1 by thefirst feed 1514-1 and (ii) the line 1508 is connected to the secondlower element 1518-2 by the second feed 1514-2. As shown, the line 1508has a meandering pattern that imparts a 180-degree phase shift toelectromagnetic signals that travel along the line 1508, relative to theelectromagnetic signals that travel along the line 1507.

The substrate 1502 includes an impedance transformer 1506 connected to aport 1512. The port 1512 is configured to receive electromagneticsignals (e.g., EM In, FIG. 15C) from one or more power amplifiers of thepower amplifier(s) 216, and provide the electromagnetic signals to theimpedance transformer 1506. As shown, the two lines 1507, 1508 arecombined and united with the impedance transformer 1506, which isconfigured to change the dipole impedance to the feed impedance.

In some embodiments, the antenna 1500 can be a single fed instead ofdifferential fed. In such a case, one of the feeds is directly connectedto the ground plane (shield) and a balun would not be needed. Further,in some embodiments, the substrate 1502 is removed and matching isachieved through a different mechanism, such as lumped components placedat an external board.

The substrate 1502 also includes a tuning stub 1510 configured to changean operating frequency (e.g., +/− approximately 25 MHz) of the antenna1500, while maintaining other radiation characteristics. In someembodiments, a connection 1511 between the tuning stub 1510 and theimpedance transformer 1506 is an electrical switch (e.g., diode or thelike), while in other embodiments the connection 1511 is a metaldeposit, such as solder. Although not shown, the tuning stub 1510 may bebroken apart at several locations, thereby allowing for various degreesof tuning. In such embodiments, a respective connection 1511 ispositioned between adjacent segments of the broken apart tuning stub1510. Electrical switches for tuning are discussed in further detailabove with reference to FIG. 11A.

FIG. 15E illustrates an antenna array 1530 that includes multipleinstances of the antenna 1500 in accordance with some embodiments. Asshown, a first antenna 1500-1 and a second antenna 1500-2 are attachedto the base 1520 and have a polarization aligned with a longestdimension of the base 1520. In some embodiments, a center-to-centerdistance between the first and second antennas 1500 is approximately 55mm (although various arrangements are possible). Because two decouplingwalls 1522 separate the first and second antennas 1500, the couplingeffect between the first and second antennas 1500 is lower relative toconventional antenna arrays. The antenna array 1530 may include morethan two instances of the antenna 1500 (e.g., the antenna array 1530 mayhave a similar configuration to the antenna array 110, or any otherantenna array described herein).

Furthermore, in some embodiments, the antenna array 1530 is combinedwith some of the other antenna arrays described herein. For example, theantenna array 1530 may be one of the antenna groups in FIG. 1 (e.g.,antenna array 1530 can be group 114-n) and another antenna arraydescribed herein (e.g., duplets 500 or 600) may be another one of theantenna groups depicted in FIG. 1.

FIG. 15F illustrates a radiation pattern 1540 generated by the antenna1500 in accordance with some embodiments. In this example, the radiationpattern 1540 has a somewhat omnidirectional pattern in the XZ-plane,with a maximum gain in the positive X-direction (with a radiation nullformed along the Y-axis), and forms an overall torus shape having a peakgain of approximately 3.65 decibels (dB). The radiation pattern 1540also has a front-to-back radiation ratio of about 5 dB.

FIG. 15G is a diagram 1550 that shows mutual coupling effects for theantenna 1500, in accordance with some embodiments. The curve S₁₁ showsthe antenna return loss, indicating an antenna operation bandwidth(S₁₁←10 dB) of 15 MHz, from 916 MHz to 930 MHz approximately.

The inventors have also discovered a number of particular arrayconfigurations that work well in implementing the transmissiontechniques discussed in reference to FIGS. 17A-20 below. For example, a2-2-2-2 array configuration and a 3-2-3 array configuration have beendiscovered.

An example of the 2-2-2-2 array configuration is shown in FIGS. 15H-2and 15H-3, and its transmission characteristics are depicted in theradiation pattern of FIG. 15J and in the return loss graph of FIG. 15K.In this example, all antennas in the array being vertically polarized,and the combination of using a 2-2-2-2 array group configuration withall antennas in the array being vertically polarized (e.g., thepolarization is perpendicular to the long side of the ground plane)results in a radiation efficiency of 64%.

An example of the 3-2-3 array configuration is shown in FIG. 15H-1, andits transmission characteristics are depicted in the radiation patternof FIG. 15I. In this example, all antennas in the array beinghorizontally polarized (e.g., the polarization is parallel to the longside of the ground plane) and, the combination of using a 3-2-3 arraygroup configuration with all antennas in the array being horizontallypolarized results in a radiation efficiency of 77%.

Thus, the inventors have discovered that the selection of the samepolarization (whether each antenna should be horizontally or verticallypolarized) is important for achieving a highest level of radiationefficiency, and that the same polarization that achieves the highestlevel of radiation efficiency may be dependent on which array groupconfiguration is used (e.g., 3-2-3 versus 2-2-2-2).

Section E.2: Second Embodiment of a Multidimensional Dipole Antenna OverFolded Shield

FIGS. 16A-16B illustrate a second embodiment of a multidimensionaldipole antenna over folded shield 1600 (referred to simply as antenna1600 below). The antenna 1600 shares many of the same components withthe antenna 1500 (and may be placed near a similar decoupling mechanism,such as decoupling walls 1622 depicted in FIG. 16B); however, ameandering pattern of the antenna 1600's radiating element 1604 differsfrom the radiating element 1504 of the antenna 1500. For example, whilethe radiating element 1604 also includes substantially symmetrical upperand lower elements, the meandering patterns of these element aresubstantially shorter than the meandering patterns of the radiatingelement 1504. In some embodiments, the radiating element 1604 is offsetin one direction to compensate for the shorter length of the radiatingelement 1604. For example, the radiating element 1604 may be verticallyoffset (up or down), and in doing so, tilting of a radiation patterncreated by the antenna 1600 with respect to broadside is reduced, and insome instances eliminated.

The other components of the antenna 1600 correspond to equivalentfeatures described above with reference to FIGS. 15A-15E. Therefore, forthe sake of brevity, the description of these features is not repeatedhere. It is noted that an antenna array may include one or moreinstances of the antenna 1600 and antenna 1500. For example, the antennaarray may include a first antenna group with instances of the antenna1600 and a second antenna group with instance of the antenna 1500. Inanother example (separate from or in addition to the previous example),the antenna array may include at least one antenna group with one ormore instances of the antenna 1500 and one or more instances of theantenna 1600. Additionally, other antennas described herein can beincluded in an antenna array that includes one or more instances of theantenna 1500 and/or the antenna 1600.

FIG. 16C illustrates a radiation pattern 1620 generated by the antenna1600. FIG. 16D illustrates a cross-sectional view 1630 of the radiationpattern 1620 shown in FIG. 16C (taken along the X-Z plane and the Y-Zplane shown in FIG. 16C). FIG. 16E is a diagram 1640 that shows returnloss for the antenna 1600.

Section F: Power Wave Transmission Techniques to Focus WirelesslyDelivered Power at a Receiving Device

As noted earlier in the Summary section, there is also a need for awireless transmission solution that complies with regulations that areconstantly evolving and that overcomes physical constraints ofconventional transmission techniques (e.g., defocusing effects). Onesuch solution is depicted and explained with reference to FIGS. 17A-20.This solution may be implemented and applied to a variety of differentantenna array configurations (e.g., any of the antenna arrays describedherein), thereby producing an antenna array the utilizes a beam-formingmethodology which allows for the antenna arrays discussed herein tocomply with governing regulations for the transmission ofelectromagnetic waves into free space. The antenna arrays, duplets, andindividual antennas discussed above may be used when implementing thisbeam-forming methodology, and specific examples of such implementationsare described below.

FIG. 17A illustrates a two-dimensional representation of a concentrationof electromagnetic energy that is produced by an antenna array inaccordance with some embodiments. As shown, a local maximum of power(P¹) is formed at a first distance away from an antenna array 1710(e.g., an instance of antenna array 110, FIG. 1) when the antenna array1710 transmits electromagnetic waves to a first focal point (V), whichcorresponds to a location of the receiver 120. As shown, the receiver120 is located at a second distance away from the antenna array 1710(the second distance is further from the antenna array 1710 than thefirst distance), and the local maximum of power (P¹) is formed at alocation that is in front of (i.e., positioned closer to the antennaarray 1710) the receiver 120's location. This result can be attributedto “defocusing,” which refers to certain effects caused by transmittedelectromagnetic waves interacting during transmission. The example oftransmitting to a single focal point (F¹) is used to demonstrate theconcept of focal shift. As explained in more detail below, certainembodiments of the antenna arrays described herein also transmit to asecond focal point (F², also shown in FIG. 17A and are thereby able tocontrol concentrations of energy in a way that ensures that thereceiver's location is within a certain distance of the local maximum ofpower and also ensures that a satisfactory roll off of the power levelis present at certain distances away from the antenna array.

The difference between a location of the local maximum of power (P¹) andthe receiver's location caused by defocusing is referred to as “focalshift,” which is the distance between the assigned focal point (F¹)(i.e., the receiver's location) and the actual location of the fieldamplitude peak (P¹). The “focal shift” typically is proportional to theassigned focal point's (F¹) distance away from the antenna array 110(i.e., as the assigned focal point's (F¹) distance away from the antennaarray 110 increases, so does the focal shift). Accordingly, problemscaused by defocusing are more pronounced with antenna arraystransmitting propagating electromagnetic waves that must travel acertain non-zero distance (e.g., 1 wavelength or greater) to reach anintended receiver.

Because governing regulations are not well-defined and are constantlyevolving and because of physical constraints of conventionaltransmission techniques (e.g., the defocusing effects discussed above),designing a power-transmission device that will comply with theseregulations is a very difficult proposition. Focal shift, in particular,must be properly accounted for in order to design antenna arrays thatwill comply with possible governing regulations.

For example, governing regulations may eventually require that: (i) athe receiver's location reside within a predefined radial distance(e.g., m*λ) from the local maximum of power (P¹), and (ii) the power,relative to the maximum power (P¹), decay by at least k dB at thepredefined radial distance (e.g., m*λ) in all directions (P²) from thelocal maximum of power (P¹) (e.g., in all sphericaldimensions/directions from P¹ away from the array). Further, in someinstances, the regulations can require some power decrease at a pointcloser to the antenna array than the local maximum of power (P¹) (i.e.,a local minimum of power is required). Additionally, in some instances,the regulations can require that a magnitude of the local maximum ofpower (P¹) is below some predefined threshold. The following equationmay represent the required power decay at the predefined radialdistance:

P ² =P ¹ −k dB

where k is a number ranging from approximately 1 dB to 6 dB (althoughthese values may change depending on a size and power delivered by theantenna array). Accordingly, transmitting devices that do not or simplycannot adequately compensate for focal shift struggle to comply with anypossible governing regulations.

In order to compensate for focal shift, the antenna array 1710 can beinstructed (e.g., by the or more processors 204 of the transmitter 102)to focus electromagnetic waves at two different focal points: a firstfocal point (F¹) and a second focal point (F²), as shown in FIG. 17A(additional examples are shown in FIGS. 18A and 19A-19D). By using twodifferent focal points, effects of focal shift are minimized (andappropriately accounted for). As a result, the transmitter 102 is ableto manage focal shift, and in turn transmit electromagnetic waves incompliance with governing regulations. A “separation distance” betweenthe first and second focal points differs depending on certainrequirements (e.g., location of the receiver, desired level of power atthe local maximum, desired power roll-off away from the local maximum,etc.), and the second focal point (F²) may or may not be within thepredefined radial distance. Creating multiple focal points, and some ofthe associated advantages, are discussed in further detail below.

FIG. 17B is a diagram 1700 that depicts power density levels relative todistance from the antenna array shown in FIG. 17A, in accordance withsome embodiments. For ease of discussion, the predefined radial distanceis defined as 1λ. However, the predefined radial distance may be othervalues, such as 0.5λ, 1.5λ, 2λ, etc., or may be defined relative to arange of values such as between 0.5λ to 2.5λ, between 0.5λ-1.5λ, between0.75λ to 1λ, etc. In some embodiments, the predefined radial distance isnot defined relative to a wavelength(“λ”) and is instead defined using aunit of length, such as feet, such that the predefined radial distancemay 0.5 feet, 1.5 feet, 2 feet, or some other appropriate value.

The illustrated diagram 1700 includes an example power profile 1702(curve shown using a dotted line) of transmitted electromagnetic wavesfor the transmission of power at-a-distance using multiple focal points.An X-axis of the diagram 1700 corresponds to the power profile's (1702)distance from the antenna array 1710 and the Y-axis of the diagram 1700corresponds to a power density of the power profile 1702 (e.g., in theaxial direction). As shown, the power profile 1702 includes a localminimum (Local Min) and a local maximum (P¹). Furthermore, thereceiver's (120) location resides within one wavelength (1λ) from thelocal maximum (P¹) and a power density of the power profile 1702 decaysby at least k dB at a distance of 1λ (P²) from the local maximum (P¹).To create the power profile 1702, the transmitter 102 can transmit someelectromagnetic waves to a first focal point (F¹) and transmit someelectromagnetic waves to a second focal point (F²), e.g., as shown inFIG. 18A.

It is also noted that the power profile 1702 represents a combined powerprofile that is produced by transmitting to two different focal points,e.g., a first power profile created by transmitting to a first focalpoint (e.g., power profile created by antenna groups 1814-4 and 1814-1,FIG. 18A) and a second power profile created by transmitting to a secondfocal point (e.g., power profile created by antenna groups 1814-2 and1814-2, FIG. 18A).

Accordingly, the example power profile 1702 illustrates that the antennaarray 1710 properly accounts for focal shift to ensure proper generationof a local maximum and appropriate decay of the power levels. Theantenna arrays discussed herein and their corresponding methods ofoperation are used to achieve such results (i.e., allowing these antennaarrays to comply with future governing regulations).

FIG. 17C is a diagram that shows power profiles with different localmaxima, in accordance with some embodiments. In particular, theprophetic diagram 1710 shows that creation of a local maximum at adistance away from the receiver's (120) location (as shown in the powerprofile 1702, which may be produced when the antenna array 1710 uses twodifferent focal points as discussed in more detail below) can result inthe received power at the receiver's location being greater than whenthe antenna array focuses all of its antennas directly at (or even past)the receiver's location (as shown in the power profile 1712). The resultshown in FIG. 17C illustrates that conventional antenna array designs(and transmission techniques associated therewith) fail to properlyaccount for defocusing effects and are thereby unable to focus power ina way that will satisfy governing regulations. Thus, the inventors havediscovered that the received power can actually be increased by creatinglocal maxima away from the receiver's location.

Additionally, when the antenna array uses at least two different focalpoints, the local maximum can be displaced closer to the receiverlocation. In addition to using at least two different focal points,instead of delivering the same transmitting power to all the antennas onthe array, the same amount of power can be redistributed such that someelements get higher power and others lower (as is explained in moredetail below, e.g. in reference to FIGS. 18A-18G), the power at thereceiver location is greater than when all antennas were focused to thereceiver location and all were excited with same amount of power.

FIGS. 18A-18G illustrate a block diagram of an antenna array 1810 inoperation that properly accounts for the effects caused by defocusing inaccordance with some embodiments. The antenna array 1810 is an exampleof the antenna array 110.

In this particular example, the antenna array 1810 includes four antennagroups 1814-A-1814-D, where each antenna group 1814 includes twoantennas 1812 (e.g., antenna duplets or any other appropriate groups ofthe antennas described herein). In some embodiments, each antenna 1812is the same antenna type while in some other embodiments one or moreantennas 1812 differ in type. As explained above with reference to FIG.1, the antenna groups 1814-A-1814-D are spaced-apart by edge-to-edgedistances (e.g., D¹ and D², FIG. 1), which may be the same or differentdistances (in certain embodiments, the center-to-center distancesbetween the respective groups of antennas may also be the same ordifferent).

In some embodiments, antennas within each group are also co-polarizedand produce perpendicularly oriented radiation patterns, as discussedabove with respect to, e.g., FIGS. 3A, 5, and 6A. It is noted that,while each antenna group 1814 includes two antennas 1812 in thisparticular example, each antenna group 1814 may include two or moreantennas, as discussed below with reference to FIG. 19A. Moreover, theantenna array 1810 may include more or less than four antenna groups. Insome embodiments, the antenna array 1810 includes instances of antenna1500 and/or antenna 1600.

Each antenna 1812 within each of the antenna groups 1814 is configuredto transmit electromagnetic waves (e.g., electromagnetic waves 1816-A,1816-B, etc.) to respective focal points (e.g., F¹ or F²) that aredetermined based on a location of the receiver 120. For example, theantennas 1812 in the second and third antenna groups 1814-2, 1814-3 areconfigured to transmit electromagnetic waves 1816-A, 1816-B to a firstfocal point (F¹), which corresponds to a location of a receiver 120. Incontrast, the antennas 1812 in the first and fourth antenna groups1814-1, 1814-4 are configured to transmit electromagnetic waves 1816-C,1816-D to a second focal point (F²), which does not correspond to thelocation of the receiver 120. Instead, the second focal point (F²) isfurther from the antenna array 1810 relative to the location of thefirst focal point (F¹). By creating two different focal points, thetransmitter 102 minimizes electromagnetic wave interaction duringtransmission, thereby minimizing (and appropriately accounting for)effects caused by defocusing, as noted above. As a result, thetransmitter 102 is able to manage focal shift, and in turn transmitelectromagnetic waves in compliance with governing regulations.Additionally, even though the local maximum (P¹) is not at thereceiver's location, the antenna array is still able to deliversufficient energy to the receiver 120 that allows the receiver toreceive operating power and/or to sufficiently charge a battery (orother power-storing component) associated therewith. The power profile1702 shown in FIG. 17B, in some instances, corresponds to thetransmission example illustrated in FIG. 18A.

A plurality of factors contributes to the effects caused by defocusing.The factors include but are not limited to: (i) values of transmissioncharacteristics (e.g., respective values for transmissioncharacteristics including power level, phase, frequency, etc.) ofelectromagnetic waves transmitted to F¹, (ii) values of transmissioncharacteristics of electromagnetic waves transmitted to F^(2,) (iii) aseparation distance (S) between the focal points, (iv) the location ofthe receiver 120 relative to the transmitter 102, and (v) a distributionof the antenna elements on the antenna array. With respect to factor(iv), in some instances, the transmitter 102 is configured to transmitelectromagnetic waves to different focal points when the location of thereceiver 120 is a sufficient distance away from the antenna array 1810(e.g., the location of the receiver 120 satisfies a threshold separationdistance). In instances where the location of the receiver 120 is not ata sufficient distance away from the antenna array 1810 (e.g., less than½ wavelength way from the antenna array), the transmitter 102 may beconfigured to transmit electromagnetic waves to a single focal point.

In some embodiments, the transmitter 102 is adapted to control alocation of a local maximum of power (e.g., P¹, FIG. 17A), a magnitudeof the local maximum of power, and a magnitude of power at thereceiver's location (e.g., control drop off from the local maximum ofpower) by changing a separation distance (S) between the two focalpoints. For example, when the separation distance (S) is a firstseparation distance, the local maximum of power is formed at a firstdistance away from the antenna array 1810 and has a first powermagnitude, and when the separation distance (S) is a second separationdistance (e.g., greater than or less than the first separationdistance), the local maximum of power is formed at a second distanceaway from the antenna array 1810 and has a second power magnitude. Inthis way, the transmitter 102 is able control power focusing of theantenna array and thereby comply with various regulations from differentgoverning bodies. As discussed below, in certain embodiments, variousbeam settings are predetermined during a configuration or setup processfor the antenna array and the transmitter performs a lookup to determinewhich of these various beam settings to use based on the receiver'scurrent location.

In order to sufficiently diminish the effects of defocusing, thetransmitter 102 selects specific values for transmission characteristics(e.g., power level, phase, etc.) of electromagnetic waves transmitted byantennas in each antenna group based on a location of the receiver 120.In the illustrated embodiment, the receiver 120 is centered with theantenna array 1810, and as a result, the electromagnetic waves 1816-A,1816-B have substantially the same values for their respectivetransmission characteristics (illustrated using a first common linepattern for electromagnetic waves 1816-A, 1816-B), and theelectromagnetic waves 1816-C, 1816-D have substantially the same valuesfor their respective transmission characteristics (illustrated using asecond common line pattern for electromagnetic waves 1816-C, 1816-D). Itis noted that the values for the electromagnetic waves 1816-A, 1816-Bdiffer from the values for the electromagnetic waves 1816-C, 1816-D.

FIGS. 18B-18E are diagrams that illustrate various axial power profilesthat can be created by the antenna array 1810 using multiple focalpoints in accordance with some embodiments. For ease of discussion andillustration, the predefined radial distance is 1λ and the required dropoff from the peak power is 3 dB (the “example power-focusingregulations”). As discussed above, the predefined radial distance andthe required drop off may also have less restrictive values (e.g., thepredefined radial distance is less than 1λ and the required drop off is1 dB) or may have more restrictive values (e.g., the predefined radialdistance is greater than 1λ and the required drop off is 4 or 5 dB). Forexplanatory purposes only, the antenna array in the depicted examplesbelow is operating at a center frequency of approximately 925 MHz.

Turning now to FIGS. 18B and 18C, example axial power profiles producedby the antenna array 1810 are illustrated, demonstrating power-focusingresults caused by adjusting a power level of transmitted electromagneticwaves, while the antennas' (1812) respective phases are fixed. Forexample, with reference to FIG. 18B, the antennas 1812 in the first andfourth antenna groups 1814-1, 1814-4 transmit electromagnetic waves with3 watts of power to the second focal point (F²), while the antennas 1812in the second and third antenna groups 1814-2, 1814-3 transmitelectromagnetic waves with 1 watt of power to the first focal point(F¹). As such, the antennas 1812 in antenna groups 1816 furthest awayfrom the receiver's 120 location transmit electromagnetic waves with ahigher power level, relative to the antennas 1812 in antenna groups 1816closest to the receiver's 120 location. As shown in FIG. 18B, the axialpower profile has a local maximum of 45.81 dB at a distance of 0.23meters from the antenna array 1810. Further, the axial power profiledecreases to 42.52 dB at 1λ from the local maximum (i.e., 3.29 dBdecrease). Accordingly, this axial power profile demonstrates that byimplementing the transmission techniques described herein, the antennaarray 1810 is capable of complying with the example power-focusingregulations defined above.

With reference to FIG. 18C, the antennas 1812 in the first and fourthantenna groups 1814-1, 1814-4 transmit electromagnetic waves with 4watts of power to the second focal point (F²) (i.e., a 1 watt increaserelative to the illustrated example of FIG. 18B), while the antennas1812 in the second and third antenna groups 1814-2, 1814-3 transmitelectromagnetic waves with 1 watt of power to the first focal point(F¹). As shown in FIG. 18C, the axial power profile has a local maximumof 46.29 dB at a distance of 0.23 meters from the antenna array 1810.Further, the axial power profile decreases to 43.14 dB at 1λ from thelocal maximum (i.e., 3.16 dB decrease). Accordingly, the axial powerprofile demonstrates that by implementing the transmission techniquesdescribed herein, the antenna array 1810 is capable of complying withthe example power-focusing regulations defined above. Moreover, incomparison with FIG. 18B, the axial power profile of FIG. 18C has ahigher local maximum with a more rapid decrease from the local maximum,demonstrating the fine-level of power-focusing control that may beachieved by implementing the transmission techniques described herein.

In some embodiments, adjusting a power level of the electromagneticwaves is performed by having the single integrated circuit discussedabove provide instructions to at least one power amplifier (e.g., one ormore of the power amplifier(s) 216, FIG. 2A). Further, in someembodiments, a first power amplifier (or one or more first poweramplifiers) is instructed to adjust power levels of one or more antennagroups of the antenna array while a second power amplifier (or one ormore second power amplifiers) is instructed to adjust power levels ofone or more different antenna groups of the antenna array. The powerfeeding circuitry 218 (FIG. 2A) may be configured to provide theelectromagnetic waves to the at least one power amplifier under controlof the single integrated circuit. In some embodiments, antenna elements1812 within a particular group have different power levels. For example,a first antenna 1812 in a first group (e.g., one of groups1814-1-1814-4) may transmit electromagnetic waves at a first powerlevel, while a second antenna 1812 in the first group may transmitelectromagnetic waves at a second power level different from the firstpower level. This level of adjustment allows the transmitter 102 toprovide granular adjustments to the antenna array, to further hone thepower profile created by the antenna array. Additionally, the individualantenna elements within a particular antenna group may be coupled to andfed by the same power amplifier or different power amplifiers.

With reference now to FIGS. 18D and 18E, power-focusing results areillustrated after adjusting phases of the antennas 1812, while a powerlevel of the transmitted electromagnetic waves is fixed. For example,with reference to FIG. 18D, the first and second antennas 1812 in thefirst and fourth antenna groups 1814-1, 1814-4, which transmit to thesecond focal point (F²), have phases of approximately 77.5 degrees and105.8 degrees, respectively (the second antenna 1812 being positionedfurther from a location of the receiver 120), while the first and secondantennas 1812 in the second and third antenna groups 1814-2, 1814-3,which transmit to the first focal point (F¹), have phases ofapproximately 6.1 degrees and 17 degrees, respectively (the firstantenna 1812 being positioned nearest a location of the receiver 120).As shown in FIG. 18D, the axial power profile has a local maximum of43.83 dB at a distance of 0.29 meters from the antenna array 1810.Further, the axial power profile decreases to 41.33 dB at 1λ from thelocal maximum (i.e., 2.5 dB decrease). Accordingly, the axial powerprofile is not in compliance with the example power-focusing regulationsdefined above.

With reference to FIG. 18E, phases of some antennas 1812 of the antennaarray 1810 have been adjusted so that the axial power profile complieswith the example power-focusing regulations. In particular, the firstand second antennas 1812 in the first and fourth antenna groups 1814-1,1814-4, which transmit to the second focal point (F²), have phases ofapproximately 93 degrees and 121 degrees, respectively, while the firstand second antennas 1812 in the second and third antenna groups 1814-2,1814-3, which transmit to the first focal point (F¹), have phases ofapproximately 6.1 degrees and 17 degrees, respectively. In other words,with respect to FIG. 18D, the phases of the first and second antennas1812 in the first and fourth antenna groups 1814-1, 1814-4 have beenadjusted. As shown in FIG. 18E, the axial power profile has a localmaximum of 44.65 dB at a distance of 0.26 meters from the antenna array1810. Further, the axial power profile decreases to 41.7 dB at 1λ fromthe local maximum (i.e., 3 dB decrease). Accordingly, the axial powerprofile is in compliance with the example power-focusing regulationsdefined above. In comparison to FIG. 18D, the axial power profile ofFIG. 18E has a higher local maximum with a more rapid decrease from thelocal maximum. Accordingly, phase adjustments can be used to increasepower and also increase power roll off.

In some embodiments, power levels and phase adjustments are made intandem to optimize the local maximum and the corresponding drop off.This level of adjustment allows the transmitter 102 to provide granularadjustments to the antenna array, to further focus the power profilecreated by the antenna array.

FIGS. 18F and 18G provide additional diagrams for the transmissionscenario illustrated in FIG. 18E. For example, FIG. 18F shows anelevation of the power profile of FIG. 18E, normalized at the localmaximum. FIG. 18G shows the power profile of FIG. 18E in the transverseplane, whereas FIG. 18E shows the power profile in the axial plane.These figures demonstrate that using the transmission techniquesdescribed herein ensures that the antenna array will satisfy the examplepower-focusing regulations in three dimensions.

FIGS. 19A-19E are block diagrams of a wireless power transmission system1900 in accordance with some embodiments. The wireless powertransmission system 1900 may be an example of the wireless powertransmission system 100 (FIG. 1). For each figure, the wireless powertransmission system 1900 includes a transmitter 102 and a receiver 120(although the wireless power transmission system could include anynumber of transmitters and receivers, as discussed with reference toFIG. 1).

The transmitter 102 includes an antenna array 1910, which is an exampleof the antenna array 110. The antenna array 1910 includes a plurality ofantenna groups 1914-1, 1914-2, . . . 1914-n, where each antenna group1914 includes a plurality of antennas 1912. The antennas 1912 in each ofthe groups can be the same antenna type or different antenna types(e.g., the antennas 1912-a . . . 1912-d may be any of the antennasdescribed herein, as well as other conventional antenna designs).Additionally, the plurality of antennas 1912 in each antenna group 1914may be coplanar and collinearly aligned with each other, and with allother antennas 1912 in the plurality of antenna groups 1914. Further,each respective antenna 1912 in each of the plurality of antenna groups1914 can have a same polarization (i.e., they are also allco-polarized). The number of antennas 1912 in each antenna group 1914may be the same (e.g., antenna array 1810, FIG. 18A) or different (e.g.,antenna array 110, FIG. 1). In some embodiments, a largestcross-sectional dimension of the antenna array is between 2λ to 3λ(determined relative to an operating frequency of the antenna array).The antenna groups of the plurality of antenna groups 1914-1, 1914-2, .. . 1914-n are spaced-apart by distances (e.g., D¹ and D², FIG. 1),which may be the same or different distances.

In certain embodiments, the antenna array is also configured as amulti-band antenna array and may also be configured to produceelectromagnetic waves having different polarizations. For example, theantennas 1912-a to 1912-d may include co-polarized antennas that produceperpendicularly oriented radiation patterns (to produce EM radiationwaves at a first frequency and with a first polarization), the antennas1912-e to 1912-h may include the antennas 1500 (to produce EM radiationat a second frequency and with a second polarization), and the antennas1912-i to 1912-1 may include co-polarized antennas that produceperpendicularly oriented radiation patterns (to produce EM radiation atthe first frequency and with the first polarization). Numerousconfigurations are within the scope of this disclosure, as will bereadily appreciated by one of skill in the art upon reading thedescriptions provided herein.

Antennas 1912 within each of the antenna groups 1914 are configured totransmit electromagnetic waves 1916-A, 1916-B, . . . 1916-N to a focalpoint (e.g., F¹ or F²). In some embodiments, antennas 1912 from one ormore antenna groups 1914 transmit electromagnetic waves to a first focalpoint (F¹), while antennas 1912 from one or more other antenna groups1914 transmit electromagnetic waves to a second focal point (F²) that isfurther from the antenna array 1910 relative to a location of the firstfocal point (F¹). The transmitter 102 is configured to assign aparticular antenna group (or one or more antennas of a particularantenna group) to a focal point based on a location of the receiver 120relative to the particular antenna group (or the antennas therein). Insome embodiments, these assignments are predetermined based on aconfiguration/setup process for the antenna array that determines allappropriate beam settings to use based on various locations of thereceiver device.

In some embodiments, antennas closest to the location of the receiver120 can be instructed to transmit waves to the first focal point (F¹)(e.g., antennas therein satisfy a first threshold distance) while otherantennas are instructed to transmit waves to the second focal point (F²)(e.g., other antennas therein satisfy a second threshold distance butfail to satisfy the first threshold distance). For example, in FIG. 19A,the receiver 120 is aligned with a center of the antenna array 1910, andas a result, antennas 1912 in the antenna group 1914-2 are closest tothe location of the receiver 120 relative to other antennas 1912 in theantenna array. Therefore, the antennas 1912 in the antenna group 1914-2are assigned to transmit to the first focal point (F¹) while antennas1912 in the other antenna groups 1914 are assigned to transmit to thesecond focal point (F²). Each focal point may have antennas from one ormore antenna groups assigned to it.

Furthermore, values for transmission characteristics (e.g., amplitude,phase, etc.) of electromagnetic waves transmitted by the assignedantennas are determined (or selected based on predetermined beamsettings) based on the location of the receiver 120 relative to theassigned antennas and/or the focal point assignment. For example, thereceiver 120 is equidistant from antennas 1912 in the antenna group1914-2, and therefore a first value for amplitude (e.g., power level—afirst transmission characteristic) is determined (or selected based onpredetermined beam settings) for the antennas 1912 in the antenna group1914-2. As such, the electromagnetic waves 1916-A are shown having afirst dash pattern, indicating that the electromagnetic waves 1916-A aretransmitted with the first value for amplitude. Values for othertransmission characteristics, such as phase, may also be determined (orselected based on predetermined beam settings).

The receiver 120 is also equidistant from antennas 1912 in the firstantenna group 1914-1 and the nth antenna group 1914-n. Therefore, asecond value for amplitude, greater than the first value, is determined(or selected based on predetermined beam settings) for the antennas 1912in these other antenna groups. Thus, the electromagnetic waves 1916-Band 1916-N are shown having a second dash pattern different from thefirst dashed pattern, indicating that the electromagnetic waves 1916-Band 1916-N are transmitted with the second value for amplitude. Again,values for other transmission characteristics, such as phase, may alsobe determined (or selected based on predetermined beam settings). Thesecond value for amplitude is greater than the first value foramplitude, in the illustrated embodiment, because electromagnetic wavestransmitted by the antennas 1912 in the first antenna group 1914-1 andthe nth antenna group 1914-n travel further than electromagnetic wavestransmitted by antennas 1912 in the second antenna group 1914-2.

In some embodiments, values for a particular transmission characteristicdiffer within a respective antenna group. For example, using the firstantenna group 1914-1 as an example, the transmitter 102 may assigndifferent values for amplitude (and/or phase) to the various antennas1912-a . . . 1912-d in the first antenna group 1914-1 based on aproximity of the antennas 1912-a . . . 1912-d to the receiver 120 (orthe assigned focal point). For example, a first antenna 1912 closest tothe receiver 120 may be assigned a first value for amplitude, a secondantenna 1912 further from the receiver 120 may be assigned a secondvalue for amplitude greater than the first value for amplitude, and soon (e.g., if the first antenna group 1914-1 includes three or moreantennas).

With reference to FIG. 19B, the receiver 120 is offset from the centerof the antenna array 1910 (e.g., offset left of center). In thisparticular example, even though the receiver 120 is offset to the left,antennas 1912 in the antenna group 1914-2 are assigned to the firstfocal point (F¹) and antennas 1912 in the other antenna groups 1914 areassigned to the second focal point (F²). However, the receiver 120 isnot equidistant from the antennas 1912 in any particular group.Accordingly, the transmitter 102 may determine (or select) differentvalues for a particular transmission characteristic for each antennagroup.

For example, a first value for amplitude may be determined for theantennas 1912 in the antenna group 1914-2, a second value for amplitudemay be determined for the antennas 1912 in the antenna group 1914-n, anda third value for amplitude may be determined for the antennas 1912 inthe antenna group 1914-1. In this particular example, the third value isgreater than the first and second values, and the second value may ormay not be greater than the first value, depending on the receiver's 120location relative to the second antenna group 1914-2 and the nth antennagroup 1914-n. Thus, the electromagnetic waves 1916-A are shown having afirst dash pattern, indicating that the electromagnetic waves 1916-A aretransmitted with the first value for amplitude, the electromagneticwaves 1916-B are shown having a second dash pattern different from thefirst dashed pattern, indicating that the electromagnetic waves 1916-Nare transmitted with the second value for amplitude, and theelectromagnetic waves 1916-B are shown having a third dash patterndifferent from the first and second dashed patterns, indicating that theelectromagnetic waves 1916-C are transmitted with the third value foramplitude.

In some embodiments, values for a particular transmission characteristicdiffer within a respective antenna group, as explained above. Forexample, within each antenna group 1914 illustrated in FIG. 19B, thetransmitter 102 may assign different values for amplitude (and/or phase)to the various antennas 1912 in each antenna group 1914 based on aproximity of the antennas 1912-a . . . 1912-b in the antenna group 1914to the receiver 120 (or the assigned focal point).

With reference to FIG. 19C, the receiver 120 is offset from the centerof the antenna array 1910 (e.g., offset right of center). The scenarioillustrated in FIG. 19C is opposite to the scenario illustrated in FIG.19B. Therefore, for the sake of brevity, a duplicative description isnot provided here.

With reference to FIG. 19D, the receiver 120 is offset from the centerof the antenna array 1910 (e.g., offset right of center). In thisparticular example, due to the receiver 120 being offset, at least oneantenna 1912 in the second antenna group 1914-2 is assigned to the firstfocal point (F¹) and at least one antenna 1912 in the first antennagroup 1914-1 is also assigned to the first focal point (F¹). Further, atleast one antenna 1912 in the second antenna group 1914-2 is assigned tothe second focal point (F²) and at least one antenna 1912 in the firstantenna group 1914-1 is also assigned to the second focal point (F²). Insuch embodiments, the transmitter 102 may determine values for aparticular transmission characteristic for each antenna 1912 within eachantenna group 1914. For example, a first value for amplitude may bedetermined for a first antenna 1914 in the second antenna group 1914-2,a second value for amplitude may be determined for a second antenna 1914in the second antenna group 1914-2 (and so on, if needed), a third valuefor amplitude may be determined for a first antenna 1914 in the firstantenna group 1914-1, a fourth value for amplitude may be determined fora second antenna 1914 in the first antenna group 1914-1, and so on asneeded. In some embodiments, the first, second, third, and fourth valuesare different, while in some embodiments one or more of the values arethe same. For example, if the receiver 120 is equidistant from antennas1912 in the first antenna group 1914-1 and antennas 1912 in the secondantenna group 1914-2, then: (i) the first and third values may be thesame and (ii) the second and fourth values may be the same, butnevertheless different from the first and third values.

In some embodiments, the position of the second focal point (F²)relative to the first focal point (F¹) changes in accordance with aposition of the receiver 120 relative to the antenna array 1910. Forexample, with reference to FIG. 19D, the second focal point (F²) isshown vertically aligned with the first focal point (F¹), even thoughthe receiver 120 is positioned right of the antenna array's 1910 center.However, the second focal point (F²) may be shifted to the right whenthe receiver 120 is right of center, such that the second focal point(F²) is no longer vertically aligned with the first focal point (F¹).The second focal point (F²) may also be shifted to the left when thereceiver 120 is left of center.

Although the illustrated embodiments show two focal points, in someembodiments, three or more focal points are used. For example, a firstfocal point is positioned at the receiver's location, while the othertwo focal points are positioned away from the receiver's location, withone of the two focal points to the left of the receiver's location andthe other of the two focal points to the right of the receiver'slocation (i.e., a triangle of focal points is formed, with a tip of thetriangle at the receiver's location). Additionally, for off centerreceiver locations, the second focal point (F²) could in general beplaced at a further apart point than the first focal point (F¹) in thedirection of a line going from the center of the array to the receiverlocation, i.e., along a slanted line. Completely horizontal alignment ofthe two focal points may also be used (e.g., the first focal point is tothe left of the receiver's location and the second focal point is to theright of the receiver's location). A general observation is that thefurther away the receiver is from the antenna array, the further awaythe second focal point has to be placed from the antenna array (i.e.,gap between the first and second focal points increases).

In some embodiments, at least one antenna group 1914 is shut off. The atleast one antenna group 1914 may be shut off when an edge-to-edgedifference between a closest antenna of the least one antenna group 1914and the receiver 120 satisfies a threshold (e.g., greater than thesecond threshold distance). In some embodiments, sufficient power can betransferred to the receiver using a subset (e.g., two) of the antennagroups and, therefore, the remaining antenna groups may be shut off forthis added reason.

FIG. 19E illustrates a system for determining values for transmissioncharacteristics in accordance with some embodiments. As shown, thetransmitter 102 includes a working (e.g., operating) space, which is anarea where the transmitter 102 may service devices in need of a charge.At least a portion of the working space may be divided into a grid 130,where each cell of the grid 1930 is associated with corresponding valuesfor one or more transmission characteristics, which may be predetermined(e.g., by having the antenna array transmit to each respective cell ofthe grid 1930 using different values for transmission characteristics ateach of the antenna groups until optimal power-focusing conditions arerealized for the respective cell, and the values that allowed theantenna array to realize the optimal power-focusing conditions are thenstored as the beam settings, which the antenna array will use once areceiver is determined to be within the respective cell).

In some embodiments, the corresponding values for the one or moretransmission characteristics are stored in the transmitter's 102 memory(e.g., memory 206, FIG. 2A). In such embodiments, the transmitter 102may include one or more beam lookup tables 240 (FIG. 2A) that store andorganize the corresponding values in a data structure for laterretrieval. The corresponding values may include values for antennas thattransmit to the first focal point (F¹) and for antennas that transmit tothe second focal point (F²). In other words, a first set ofcorresponding values is selected to direct waves to the first focalpoint (F¹) and a second set of corresponding values is selected todirect waves to the second focal point (F²).

To illustrate, the transmitter 102 can determine that the receiver 120is located within Zone 3 of the grid 1930. In response to determiningthat the receiver 120 is located within Zone 3 of the grid 1930, thetransmitter 102 determines (e.g., retrieves using a lookup table) valuesfor the one or more transmission characteristics based on the receiver120 being located within Zone 3 of the grid 1930. For example, thetransmitter 102 may reference a beam lookup table 240 stored in memory206 to find the appropriate values for one or more transmissioncharacteristics when a receiver 120 is located within Zone 3 of the grid1930.

In another example, the transmitter 102 may compute the appropriatevalues for the one or more transmission characteristics dynamically. Theappropriate values may include values for antennas that transmit to thefirst focal point (F¹) (i.e., the receiver's 120 location) and forantennas that transmit to the second focal point (F²). It is noted thatthe size of each cell can vary depending on the circumstance, and theexample size dimensions depicted in FIG. 19E are non-limiting examplesused for illustrative purposes.

In some embodiments, each antenna group is shut off when the transmitter102 detects a person or animal (or some other sensitive object) within apredefined region of the working space (e.g., shaded “Shut-off Region”shown in FIG. 19E). Each antenna group is shut off to avoid exposing anysensitive objects to the electromagnetic energy, e.g., because a powerlevel of the electromagnetic energy in the Shut-off Region is higherthan a power level of the electromagnetic energy in other regions of theworking space when the antenna array is operating (e.g., area left ofLocal Min in FIG. 17B may correspond to the “Shut-Off area”). Thepredefined region may extend the length (or some distance less than thelength) of the transmitter 102.

FIG. 20 is a flow diagram showing a method 2000 of wireless powertransmission in accordance with some embodiments. Operations (e.g.,steps) of the method 2000 may be performed by a controller of atransmitter (e.g., processor(s) 204 of transmitter 102, FIG. 2A, whichmay be the single integrated circuit discussed above in reference toFIG. 2A). At least some of the operations shown in FIG. 20 correspond toinstructions stored in a computer memory or computer-readable storagemedium (e.g., memory 206 of the transmitter 102, FIG. 2A).

The method 2000 is performed (2002) at a wireless-power-transmittingdevice (e.g., transmitter 102, FIG. 1) that includes an antenna array(e.g., antenna array 1910, FIG. 19A), the antenna array including afirst antenna group (e.g., antenna group 1914-2, FIG. 19A) of at leasttwo antennas (e.g., antennas 1912-e . . . 1912-h shown in the antennagroup 1914-n) and a second antenna group of at least two antennas (e.g.,antennas 1912-a . . . 1912-d shown in antenna group 1914-n) distinctfrom the first antenna group. The wireless-power-transmitting device maybe in communication with a controller (e.g., processor(s) 204 oftransmitter 102, FIG. 2A) that performs (or causes performance of) theoperations discussed below. In some embodiments, the at least twoantennas in the first antenna group and the at least two antennas in thesecond antenna group are co-planar (e.g., each antenna extends away fromthe antenna array 110 to the same height, thereby having a commonplane). In addition, the at least two antennas in the first antennagroup and the at least two antennas in the second antenna group may becollinearly aligned along an axis (e.g., antennas 1912 shown in FIG. 19Aare collinearly aligned along an axis running the length of the antennaarray 1910).

In some embodiments, antennas within each group are also co-polarizedand have perpendicular radiation patterns, as discussed in more detailwith respect to FIGS. 3-9. Any of the antennas exhibiting thesecharacteristics (such as those discussed with respect to FIGS. 10-16)may be used within these antenna groups. In some embodiments, theantenna array is a miniaturized antenna array in which each of theantennas in the first and second antenna groups of antennas has alargest dimension of less than 0.25λ in size.

In some embodiments, the antenna array includes a third antenna groupwith at least two antennas (e.g., antennas 1912-i . . . 1912-1 shown inantenna group 1914-1, FIG. 19A) distinct from the first and secondantenna groups. In such embodiments, the first antenna group (e.g.,group 1914-2, FIG. 19A) is positioned between the second and thirdantenna groups within the antenna array, and the first antenna group isseparated from the second and third antenna groups by at least anon-zero spacing distance. Furthermore, the at least two antennas in thefirst antenna group are positioned in a central region of the antennaarray, and the respective at least two antennas of each of the secondand third antenna groups are positioned near opposing edge regions ofthe antenna array. In some embodiments, the second and third antennagroups include a same number of antennas, and the first antenna groupincludes fewer than the same number of antennas (or vice versa).Alternatively, in some embodiments, each antenna group includes the samenumber of antennas (e.g., antenna groups 1814-1-1814-4 include the samenumber of antennas, FIG. 18A).

In some embodiments, the method 2000 includes receiving (2004) a signalfrom a wireless-power-receiving device (e.g., receiver 120, FIG. 1) fromwhich a location of the wireless-power-receiving device is determined.In some embodiments, the transmitter 102 determines the location of thewireless-power-receiving device based on signal strength of the signal,triangulation, and/or response time (e.g., the receiver 120 timestampsthe signal when sent which is then compared against a timestamp of thesignal when it is received at the transmitter). Alternatively or inaddition, the method 2000 includes (i) detecting a phase of the signaland (ii) determining the location of the receiver device relative to theantenna array based on the phase of the signal. In some embodiments, thereceiving device transmits its precise location (e.g., within 0.5 cm) tothe transmitting device. In some embodiments, the receiving deviceincludes a location detection device, such as a GPS (global positioningsatellite or the like) or other geo-location receiver, for determiningits location, and sends corresponding GPS-data to the transmitter in thesignal. In some embodiments, the location is an estimated or approximatelocation of the wireless-power-receiving device. In such embodiments,the receiver may be determined to be within a particular predeterminedportion of the transmission field of the transmitter 102, based on theestimation (e.g., determined to be within one of the Zones/cellsillustrated in FIG. 19E).

In some embodiments (in addition to or as an alternative to step 2004),the location of the wireless-power-receiving device is determined byfirst determining an optimal phase on each transmitting antenna elementthat maximizes received power, which is accomplished by rotating thefeed phase of antenna elements and monitoring the received power. Thereare several ways of doing the above, including: (i) starting with allantennas activated (i.e., on), transmit at a known or arbitrary phase,sequentially scan the phase for each antenna element and monitorreceived power, and record the optimal phase that maximizes receivedpower; (ii) starting with only one reference antenna activated,sequentially activate a second antenna, scan the phase of the secondantenna while monitoring received power, record the optimal phase thatmaximizes received power, switch the antenna off, and repeat thisprocedure until all transmitting antennas have been calibrated; and(iii) starting with only one reference antenna activated, sequentiallyactivate each antenna while scanning the phase of the newly activatedantenna, and then keep adding antennas until all transmitting antennasare activated (or any combination of (i)-(iii)). Once the optimal phasethat maximizes received power is determined, then the method 2000 mayinclude determining the location of the wireless-power-receiving devicebased on the determined optimal phase.

In some embodiments, the wireless-power-receiving device includes anelectronic device (e.g., mobile phone, watch, TV remote, battery, etc.)and wireless power receiving circuitry (e.g., a receiver 120, whichincludes power receiver antennas, rectifier circuitry, and a powerconverter) that is coupled with the electronic device (e.g., embedded inor integrated with the electronic device).

In some embodiments, the method 2000 includes, based on the location ofthe wireless-power-receiving device, selecting (2006) (i) a first valuefor a first transmission characteristic that is used for transmission ofelectromagnetic waves by the at least two antennas in the first antennagroup, and (ii) a second value, distinct from the first value, for thefirst transmission characteristic that is used for transmission ofelectromagnetic waves by the at least two antennas in the second antennagroup. For example, as discussed below, these values can be a preferredamplitude, phase, and/or polarization of the signal. In someembodiments, the second value is greater than the first value (e.g.,when the receiver 120 is closest to the first antenna group).Additionally, the first and second values can be determined dynamicallyor they can be predetermined. Moreover, in some embodiments, the firstand second values are stored in a lookup table (e.g., beam lookuptable(s) 240, FIG. 2A). In such embodiments, selecting (2006) the firstand second values includes obtaining the first and second values fromthe lookup table.

In some embodiments, before selecting (2006) the first and secondvalues, the method 2000 includes determining that the location of thewireless-power-receiving device is within a first cell of a plurality ofcells (e.g., Zone 3 of the grid 1930, FIG. 19E). In such embodiments,selecting (2006) the first and second values includes using valuesassigned the first cell, which may be stored in the lookup table.Selecting values for transmission characteristics using the grid 1930 isdiscussed in detail with reference to FIG. 19E.

The first transmission characteristic can be amplitude (e.g., powerlevel value) for the transmission of electromagnetic waves. In someembodiments, the wireless-power-transmitting device selects additionalvalues for other transmission characteristics as well. For example, thewireless-power-transmitting device may also select respective values forphase, polarization, etc. Selecting values for transmissioncharacteristics is discussed in further detail above with reference toFIGS. 19A-19E.

In some embodiments, the method 2000 includes transmitting (2008) to thelocation of the wireless-power-receiving device, by the at least twoantennas in the first antenna group, first electromagnetic waves havingthe first value for the first transmission characteristic. For example,with reference to FIG. 19A, antennas 1912-e . . . 1912-h shown inantenna group 1914-2 are transmitting electromagnetic waves 1916-A to alocation of the receiver 120 (e.g., transmit to a first focal point(F¹)). The electromagnetic waves 1916-A are shown having a first dashpattern, indicating that the electromagnetic waves 1916-A aretransmitted with the first value for the first transmissioncharacteristic.

In some embodiments, the method 2000 includes transmitting (2010) to afocal point that is further from the wireless-power-transmitting devicethan the location of the wireless-power-receiving device, by the atleast two antennas in the second antenna group, second electromagneticwaves with the second value for the first transmission characteristic.For example, with reference to FIG. 19A, antennas 1912-a . . . 1912-dshown in antenna group 1914-n (or antennas 1912-i . . . 1912-l shown inantenna group 1914-1) are transmitting electromagnetic waves 1916-N to asecond focal point (F²), where F² is further from the transmitter 102than the location of the receiver 120 (a first focal point (F¹) is atthe receiver's location). The electromagnetic waves 1916-B are shownhaving a second dash pattern different from the first dashed pattern,indicating that the electromagnetic waves 1916-B are transmitted withthe second value for the first transmission characteristic. Transmittingelectromagnetic waves to focal points is discussed in further detailabove with reference to FIGS. 18A-18C and 19A-19E.

The wireless-power-receiving device uses energy from at least the firstelectromagnetic waves to power or charge the wireless-power-receivingdevice. Stated another way, transmission of the first and secondelectromagnetic waves produces a level of electromagnetic energy nearthe location of the wireless-power-receiving device (e.g., as shown inFIG. 17B's power profile 1702) and the wireless-power-receiving uses theEM energy (i.e., at least some of the level of EM energy) to power orcharge the wireless-power-receiving device.

In some embodiments, before selecting (2006) the first and second valuesand the transmitting steps (2008) and (2010), the method 2000 includesdetermining that the location of the wireless-power-receiving device isa sufficient distance away from the antenna array (e.g., a separationdistance between the wireless-power-receiving device and the antennaarray satisfies a threshold separation distance, such as the receivingdevice being located 12 cm or more away from the transmitting device).In accordance with a determination that the location of thewireless-power-receiving device is a sufficient distance away from theantenna array, the method 2000 proceeds to the selecting (2006) and thetransmitting steps (2008) and (2010). And, in accordance with adetermination that the location of the wireless-power-receiving deviceis not a sufficient distance away from the antenna array (i.e., thewireless-power-receiving device is close to the antenna array, such ascloser that one wavelength or a half wavelength), the method 2000includes transmitting to the location of the wireless-power-receivingdevice, by the at least two antennas in the first and second antennagroups, the first and second electromagnetic waves (i.e., a single focalpoint is used).

In some embodiments, the location of the wireless-power-receiving deviceis positioned along an axis extending away from the antenna array andthe focal point is further from the antenna array along the axis. Inother words, the location of the wireless-power-receiving device and thefocal point are co-axially positioned with respect to thewireless-power-transmitting device. For example, with reference to FIG.19A, the location of the wireless-power-receiving device and the secondfocal point (F²) are vertically aligned. Alternatively, in someembodiments, the focal point is offset from the position of thewireless-power-receiving device in a direction (e.g., as shown in FIGS.19C and 19D).

In some embodiments, transmission of the first and secondelectromagnetic waves generates a local minimum of electromagneticenergy at a first distance from the antenna array (e.g., Local Min, FIG.17B), and a local maximum of electromagnetic energy at a second distancegreater than the first distance from the antenna array (e.g., Local Max,FIG. 17B). Further, the location of the wireless-power-receiving devicemay be at a third distance greater that the second distance from theantenna array. For example, with reference to FIG. 17B, the localminimum and maximum are formed at two different distances, and thelocation of the receiver 120 is at some distance greater than the twodifferent distances.

Moreover, in some embodiments, the first and second electromagneticwaves have a wavelength (λ) and a difference between the second andthird distances is less than or equal to m*λ, where “m” is a number thatmay range from approximately 0.25 to 5. Furthermore, in someembodiments, the local maximum of electromagnetic energy has a firstpower level and transmission of the first and second electromagneticwaves generates a concentration (e.g., a sphere) of electromagneticenergy having a second power level at a distance of m*λ from the localmaximum. The second power level is less than the first power level by apredetermined amount. The predetermined amount may range from 0.5 dB to5 dB, although greater values are possible depending on the application(e.g., depending on a size and feed power of the antenna array). Theconcentration of electromagnetic energy is discussed in further detailabove with reference to FIGS. 17A-17B.

In those embodiments where the antenna array includes the third antennagroup, the method 2000 includes transmitting (2012), to the focal pointthat is further from the wireless-power-transmitting device than thelocation of the wireless-power-receiving device, by the at least twoantennas in the third antenna group, third electromagnetic waves withthe second value for the first transmission characteristic. For example,with reference to FIG. 19A, antennas 1912-i . . . 1912-l shown inantenna group 1914-1 are transmitting electromagnetic waves 1916-B tothe second focal point (F²), where F² is further from the transmitter102 than the location of the receiver 120. The electromagnetic waves1916-B are shown having the second dash pattern different from the firstdashed pattern, indicating that the electromagnetic waves 1916-N aretransmitted with the second value for the first transmissioncharacteristic. In some embodiments, electromagnetic waves 1916-B aretransmitted with a third value for the first transmission characteristicdifferent from the first and second values (e.g., when the receiver 120is offset left of center or right of center, FIGS. 19C and 19D).

In some embodiments, the selecting (2006) also includes selectingrespective phase settings for (i) each antenna of the at least twoantennas in the first antenna group, (ii) each antenna of the at leasttwo antennas in the second antenna group, and (iii) optionally eachantenna of the at least two antennas in the third antenna group.Further, in some embodiments, respective phase settings for the at leasttwo antennas in the second antenna group and respective phase settingsfor the at least two antennas of the third antenna group are the same.However, in some embodiments, the respective phase settings for the atleast two antennas in each group may differ. Selecting phase settings isdiscussed in further detail above with reference to FIGS. 18D and 18E.

As noted above, in some embodiments, antennas within each group of theantenna array are also co-polarized (i.e., they have a samepolarization). The inventors have discovered that the selection of thesame polarization (whether each antenna should be horizontally orvertically polarized) is important for achieving a highest level ofradiation efficiency (as was discussed above), and that the samepolarization that achieves the highest level of radiation efficiency isdependent on which array group configuration is used. For example, whenthe 3-2-3 array group configuration is used (e.g., three antennas in afirst antenna group, two antennas in a second antenna group, and threeantenna in a third antenna group, as shown in FIG. 15H-1), the inventorshave discovered that the same polarization is horizontal relative to asurface of the antenna array on which of the antennas of each of thegroups is placed (e.g., as shown on FIG. 15H-1, the combination of usinga 3-2-3 array group configuration with all antennas in the array beinghorizontally polarized results in a radiation efficiency of 77%). Asanother example, when the 2-2-2-2 array group configuration is used, thesame polarization is vertical relative to a surface of the antenna arrayon which the antennas of each of the groups is placed (e.g., as shown onFIG. 15H-3, the combination of using a 2-2-2-2 array group configurationwith all antennas in the array being vertically polarized results in aradiation efficiency of 64%). These specific array group configurationsare just examples and numerous other configurations are also describedherein and will be readily apparent to one of skill in the art uponreading this description.

FIG. 21 is a flow diagram showing a method 2100 of wireless powertransmission in accordance with some embodiments. Operations (e.g.,steps) of the method 2100 may be performed by a controller of atransmitter (e.g., processor(s) 204 of transmitter 102, FIG. 2A, whichmay be the single integrated circuit discussed above in reference toFIG. 2A). At least some of the operations shown in FIG. 21 correspond toinstructions stored in a computer memory or computer-readable storagemedium (e.g., memory 206 of the transmitter 102, FIG. 2A).

The method 2100 is performed (2102) at a wireless-power-transmittingdevice (e.g., transmitter 102, FIG. 1) that includes an antenna array(e.g., antenna array 1910, FIG. 19A, antenna array 1810, FIG. 18A,etc.). In some embodiments, the antenna array includes a first antennagroup of at least two antennas and a second antenna group of at leasttwo antennas distinct from the first antenna group (2112). The first andsecond antenna groups may be composed of one or more of the antennagroups illustrated in FIGS. 18A-19E. A structure of thewireless-power-transmitting device is described in further detail abovewith reference to the method 2000 (e.g., step 2002).

In some embodiments, the method 2100 includes detecting (2104) alocation of a wireless-power-receiving device. For example, thewireless-power-receiving device may send a signal to thewireless-power-transmitting device from which a location of thewireless-power-receiving device is determined. Detecting a location ofthe wireless-power-receiving device is discussed in further detail abovewith reference to the method 2000 (e.g., step 2004).

In some embodiments, the method 2100 includes determining (2106)settings for electromagnetic waves based on the location of thewireless-power-receiving device relative to the antenna array. Forexample, the wireless-power-transmitting device may select values fortransmission characteristics used for transmission of theelectromagnetic waves. Selecting values for transmission characteristicsis discussed in further detail above with reference to the method 2000(e.g., step 2006) and FIGS. 19A-19E.

The method 2100 includes radiating (2108) electromagnetic waves thatform a maximum power level at a first distance away from the antennaarray. A power level of the radiated electromagnetic waves decreases,relative to the maximum power level, by at least a predefined amount ata predefined radial distance away from the maximum power level. Forexample, with reference to FIGS. 17A and 17B, the predefined radialdistance from the maximum power level (P¹) is, say, 1λ, and a powerlevel at P² drops by a predefined amount from the maximum power level(P¹) (e.g., the drop is shown in FIG. 17B). In some embodiments, thepredefined amount is an amount that ranges from approximately 1 to 7 dB.In some other embodiments, the predefined amount is an amount thatranges from approximately 2 to 5 dB. In some other embodiments, thepredefined amount is approximately 3 dB (2110). P¹ and P² are discussedin further detail above with reference to FIGS. 17A-18A.

As noted above, in some embodiments, the antenna array includes firstand second groups of antennas (2112). In such embodiments, when thewireless-power-transmitting device radiates the electromagnetic waves(2108), the wireless-power-transmitting device radiates (2114) a firstplurality of electromagnetic waves from antenna elements in the firstgroup of antennas using first settings from the determined settings. Afirst transmission focal point for the antenna elements in the firstgroup of antennas is the location of the wireless-power-receiving device(e.g., F¹, FIG. 18A).

Further, the wireless-power-transmitting device also radiates (2116) asecond plurality of electromagnetic waves from antenna elements in thesecond group of antennas using second settings, different from the firstsettings, from the determined settings. The antenna elements in thesecond group of antennas have a second transmission focal point (e.g.,F², FIG. 18A) that is another location further from the antenna arraythan the location of the wireless-power-receiving device. As an example,with reference to FIG. 18B, the antennas 1812 in the first and fourthantenna groups 1814-1, 1814-4 transmit electromagnetic waves with 3watts of power to the second focal point (F²), while the antennas 1812in the second and third antenna groups 1814-2, 1814-3 transmitelectromagnetic waves with 1 watt of power to the first focal point(F¹). As such, the antennas 1812 in antenna groups furthest away fromthe receiver's 120 location transmit electromagnetic waves with a higherpower level, relative to the antennas 1812 in antenna groups closest tothe receiver's 120 location. Additional examples are discussed abovewith reference to FIGS. 18C-18E, and FIGS. 19A-19E.

The terminology used in the description of the invention herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of the invention. As used in the description ofthe invention and the appended claims, the singular forms “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will also be understood that theterm “and/or” as used herein refers to and encompasses any and allpossible combinations of one or more of the associated listed items. Itwill be further understood that the terms “comprises” and/or“comprising,” when used in this specification, specify the presence ofstated features, steps, operations, elements, and/or components, but donot preclude the presence or addition of one or more other features,steps, operations, elements, components, and/or groups thereof.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Many modificationsand variations are possible in view of the above teachings. Theembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, to therebyenable others skilled in the art to best utilize the invention andvarious embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A method, comprising: at awireless-power-transmitting device that includes an antenna array:radiating electromagnetic waves that form a maximum power level at afirst distance away from the antenna array, wherein a power level of theradiated electromagnetic waves decreases, relative to the maximum powerlevel, by at least a predefined amount at a predefined radial distanceaway from the maximum power level.
 2. The method of claim 1, wherein: awireless-power-receiving device is located a second distance, greaterthan the first distance, away from the antenna array; and thewireless-power-receiving device is located within the predefined radialdistance away from the maximum power level.
 3. The method of claim 2,wherein the wireless-power-receiving device uses energy from theradiated electromagnetic waves to power or charge thewireless-power-receiving device.
 4. The method of claim 2, wherein thedecrease in the power level of the radiated electromagnetic waves fromthe maximum power level is a monotonic decrease.
 5. The method of claim1, wherein: the radiated electromagnetic waves have a frequency and awavelength (λ); and the predefined radial distance ranges fromapproximately 0.5λ to 2λ.
 6. The method of claim 5, wherein thepredefined radial distance is approximately 1λ.
 7. The method of claim1, further comprising, before radiating the electromagnetic waves:detecting a location of a wireless-power-receiving device, wherein thelocation of the wireless-power-receiving device is further from theantenna array than a location of the maximum power level.
 8. The methodof claim 7, further comprising: after detecting the location of thewireless-power-receiving device and before radiating the electromagneticwaves: determining settings for the electromagnetic waves based on thelocation of the wireless-power-receiving device relative to the antennaarray.
 9. The method of claim 8, wherein the electromagnetic waves areradiated using the determined settings.
 10. The method of claim 9,wherein: the antenna array includes first and second groups of antennas;radiating the electromagnetic waves comprises: radiating a firstplurality of electromagnetic waves from antenna elements in the firstgroup of antennas using first settings from the determined settings,wherein a first transmission focal point for the antenna elements in thefirst group of antennas is the location of the wireless-power-receivingdevice; and radiating a second plurality of electromagnetic waves fromantenna elements in the second group of antennas using second settings,different from the first settings, from the determined settings, whereinthe antenna elements in the second group of antennas have a secondtransmission focal point that is another location that is further fromthe antenna array than the location of the wireless-power-receivingdevice.
 11. The method of claim 1, wherein the predefined amount is anamount that ranges from 1 to 7 dB.
 12. The method of claim 11, whereinthe predefined amount is an amount that ranges from 2 to 5 dB.
 13. Themethod of claim 12, wherein the predefined amount is approximately 3 dB.14. A wireless-power-transmitting device comprising: an antenna array;one or more processors; and memory storing one or more programs forexecution by the one or more processors, the one or more programsincluding instructions for: radiating electromagnetic waves that form amaximum power level at a first distance away from the antenna array,wherein a power level of the radiated electromagnetic waves decreases,relative to the maximum power level, by at least a predefined amount ata predefined radial distance away from the maximum power level.
 15. Thewireless-power-transmitting device of claim 14, wherein the one or moreprograms further include instructions for, before radiating theelectromagnetic waves: detecting a location of awireless-power-receiving device, wherein the location of thewireless-power-receiving device is further from the antenna array than alocation of the maximum power level.
 16. The wireless-power-transmittingdevice of claim 15, wherein the one or more programs further includeinstructions for: after detecting the location of thewireless-power-receiving device and before radiating the electromagneticwaves: determining settings for the electromagnetic waves based on thelocation of the wireless-power-receiving device relative to the antennaarray.
 17. The wireless-power-transmitting device of claim 16, wherein:the antenna array includes first and second groups of antennas;radiating the electromagnetic waves comprises: radiating a firstplurality of electromagnetic waves from antenna elements in the firstgroup of antennas using first settings from the determined settings,wherein a first transmission focal point for the antenna elements in thefirst group of antennas is the location of the wireless-power-receivingdevice; and radiating a second plurality of electromagnetic waves fromantenna elements in the second group of antennas using second settings,different from the first settings, from the determined settings, whereinthe antenna elements in the second group of antennas have a secondtransmission focal point that is another location that is further fromthe antenna array than the location of the wireless-power-receivingdevice.
 18. The wireless-power-transmitting device of claim 14, wherein:the radiated electromagnetic waves have a frequency and a wavelength(λ); and the predefined radial distance ranges from approximately 0.5λto 2λ.
 19. The wireless-power-transmitting device of claim 18, whereinthe predefined radial distance is approximately 1λ.
 20. A non-transitorycomputer-readable storage medium, storing one or more programsconfigured for execution by one or more processors of awireless-power-transmitting device that includes an antenna array, theone or more programs including instructions for: radiatingelectromagnetic waves that form a maximum power level at a firstdistance away from the antenna array, wherein a power level of theradiated electromagnetic waves decreases, relative to the maximum powerlevel, by at least a predefined amount at a predefined radial distanceaway from the maximum power level.